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REPORT 

OF  THE 

COMMITTEE   ON  EDITING  TENTATIVE 
AND  OFFICIAL 

Methods  of  Analysis 


THE  ASSOCIATION  OF  OFFICIAL  AGRICULTURAL  CHEMISTS 

WILLIAMS  &  WILKINS  COMPANY 

BALTIMORE.  U.  S.  A. 

1916 


5 


f\l^ 


MAIN  imRARY  AGRIC.  DEPT. 

COPTRIQHT,    1916 
BY 

The  Association  of  Official  Aqeicui-tural  Chemists 


COMPOSED  AND  PRINTED  ATTHK 

WAVERLY  PRESS 

Bt  THB  WiLIJAMS  &  WiLKINS  COMPAHT 

Baltimore,  Md.,  U.  8  A. 


CONTENTS 

I.  Fertilizers 1 

II.  Soils 17 

III.  Plant  Constituents 29 

IV.  Waters 35 

V.  Tanning  Materials 53 

VI.  Leathers 59 

VII.  Insecticides  and  Fungicides 63 

VIII.  Foods  and  Feeding  Stuffs 79 

IX.  Saccharine  Products 121 

X.  Food  Preservatives 141 

XI.  Coloring  Matters  in  Foods 155 

XII.  Metals  in  Foods 171 

XIII.  Fruits  and  Fruit  Products 177 

XIV.  Canned  Vegetables 185 

XV.  Cereal  Foods 187 

XVI.  Wines 193 

XVII.  Distilled  Liquors 243 

XVIII.  Beers 249 

XIX.  Vinegars 253 

XX.  Flavoring  Extracts 259 

XXI.  Meat  and  Meat  Products 271 

XXII.  Dairy  Products 287 

XXIII.  Fats  and  Oils 299 

XXIV.  Spices  and  Other  Condiments 317 

XXV.  Cacao  Products 327 

XXVI.  Coffees 331 

XXVII.  Tea 335 

XXVIII.  Baking  Powders  and  Their  Ingredients 339 

XXIX.  Drugs 351 

Index 367 


793413 


ILLUSTRATIONS 

Figure    1.  Combustion  tube  for  the  determination  of  total  nitrogen 9 

Figure    2.  Parr's  apparatus  for  the  determination  of  carbon  dioxid 18 

Figure    3.  Modified  Marr  apparatus  for  determining  carbon  dioxid 19 

Figure    4.  Metal  extractor  used  for  extracting  tanning  materials 56 

Figure    5.  Apparatus  for  distillation  of  arsenic  chlorid 64 

Figure    6.  Apparatus  for  detection  of  formic  acid 153 

Figure    7.  Apparatus  for  the  determination  of  arsenic 172 

Figure    8.  Apparatus  for  the  determination  of  volatile  acids 239 

Figure    9.  Apparatus  for  the  Folin  ammonia  determination 275 

Figure  10.  Van  Slyke  apparatus  for  the  determination  of  amino  nitrogen 282 

Figure  11.  Details  of  the  deaminizing  bulb  and  connection 283 

Figure  12.  Apparatus  for  the  melting  point  determination 303 

Figure  13.  Apparatus  for  the  determination  of  the  Polenske  number 309 

Figure  14.  Knorr's  apparatus  for  the  determination  of  carbon  dioxid 339 

Figure  15.  Heidenhain's  apparatus  for  the  determination  of  carbon  dioxid 341 


TABLES 

Table  1.  Munson  and  Walker's  Table.  For  calculating  dextrose,  invert  sugar 
alone,  invert  sugar  in  the  presence  of  sucrose  (0.4  gram  and  2  grams 
total  sugar),   lactose   (two  forms),   and  maltose   (anhydrous  and 

crystallized) 88 

Table  2.  Herzfeld's  Table.  For  the  determination  of  invert  sugar  in  mate- 
rials containing  1.5%,  or  less,  of  invert  sugar  and  98.5%,  or  more, 

of  sucrose 99 

Table  3.  Meissl  and  Killer's  factors  for  determinations  in  materials  in  which, 
of  the  total  sugars  present,  1.5%,  or  more,  is  invert  sugar,^  and  98.5%, 

or  less,  is  sucrose 100 

Table    4.  Meissl's  Table.    For  the  determination  of  invert  sugar  alone 101 

Table    5.  For  the  determination  of  maltose 103 

Table    6.  For  the  determination  of  lactose 105 

Table    7.  AUihn's  Table.     For  the  determination  of  dextrose 107 

Table    8.  Krober's  Table.     For  determining  pentoses  and  pentosans 112 

Table    9.  For  correction  of  the  readings  of  the  Brix  spindle  when  made  at  other 

than  the  standard  temperature,  17.5°C 123 

Table  10.  For  the  comparison  of  specific  gravities  at  j^g,  ",  degrees  Brix  and 

degrees  Baume 124 

Table  11.  Densities  of  solutions  of  cane  sugar  at  20°C 125 

Table  12.  Geerlig's  Table.     For  dry  substance  in  sugar-house  products  by  the 

Abbe  ref ractometer,  at  2S°C 127 

Table  13.  Corrections  for  temperature 128 

Table  14.  Color  reactions  produced  on  dyed  fibers  by  various  reagents 161 

Table  15.  Behavior  of  certain  natural  coloring  matters  with  common  reagents..  166 
Table  16.  Alcohol  Table.     For  calculating  the  percentages  of  alcohol  in  mix- 
tures of  ethyl  alcohol  and  water  from  their  specific  gravities 194 

Table  17.  Alcohol  Table.  For  calculating  the  percentages  of  alcohol  in  mix- 
tures of  ethyl  alcohol  and  water  from  their  Zeiss  immersion  refrac- 

tometer  readings  at  17.5°-25°C 208 

Table  18.  Scale  readings  of  the  Zeiss  immersion  refractometer  at  20''C.,  corre- 
sponding to  each  per  cent  by  weight  of  methyl  and  ethyl  alcohols. .   247 
Table  19.  Volumes  of  milk  corresponding  to  a  lactose  double  normal  weight . . .    288 
Table  20.  Butyro-ref ractometer  readings  and  indices  of  refraction 301 


REPORT   OF  THE  COMMITTEE   ON   EDITING  METHODS 
^  —OF  ANALYSIS. 

Washington,  D.  C,  NovemlxM-  16,   191;"). 

To  The  President  and  Members  of  the/ Association  of  Official  Agricul- 
tural Chemists.  1— 
Gentlemen: — Your  committee  on  editing  methods  of  analysis  begs  leave  to  report 
that  it  has  completed  the  work  assigned  and  herewith  submits  for  your  consideration 
the  revised  methods.  The  committee  has  included  all  authorized  changes  and  addi- 
tions, has  eliminated  obsolete  methods  in  so  far  as  possible,  rewritten  the  text  where 
parts  appeared  obscure,  and  made  such  consolidations  of  general  methods  and 
rearrangements  as  in  its  opinion  would  promote  brevity  and  clearness. 

In  order  that  the  members  of  the  Association  may  have  an  opportunity  to  criti- 
cize the  revised  methods  it  is  suggested  by  your  committee  that  this  report  be 
published  in  the  Journal  of  the  Association  with  a  view  to  final  adoption  of  the 
metliods  in  19IG. 

Respectfully  submitted, 

Committee  on  Editing  Methods  of  Analysis. 
R.  E.  DooLiTTLE,  Chairman,     A.  F.  Seeker, 
W.  A.  Withers,  G.  W.  Hoover, 

J.  P.  Street,  B.  L.  Hartwell. 

Editorial  Note: — The  Board  of  Editors  submits  the  following  comment  upon  the 
report  of  the  Committee  on  Editing  Methods  of  Analysis: 

Inasmuch  as  the  methods  of  analysis  as  prescribed  by  this  Association  have  been 
adopted,  by  regulation,  for  the  enforcement  of  the  Federal  Food  and  Drugs  Act 
and,  by  law,  in  many  of  the  States  for  the  enforcement  of  State  laws,  certain  safe- 
guards to  protect  their  integrity  are  provided  by  the  Association's  Constitution 
and  By-Laws. 

The  Constitution  and  By-Laws  provide  for  Official  and  Provisional  Methods 
only.  At  the  last  meeting  of  the  Association  it  was  suggested  that  the  "Provisional" 
methods  be  designated  as  '"Tentative"  and  the  committee  was  instructed  at  the 
afternoon  session,  Wednesdaj',  November  17,  1915,  to  make  their  report  accordingly. 
The  phraseology  of  the  Constitution  was  not  changed,  however,  but  was  referred 
to  a  committee  to  be  reported  upon  at  the  1916  meeting.  Therefore,  in  the  present 
report  the  word  "Tentative"  has  been  substituted  for  the  word  "Provisional", 
though  the  term  "Provisional"  must  be  formally  retained  until  the  Constitution 
shall  have  been  changed. 

Changes  in  methods  cannot  be  made  until  an  opportunity  has  been  given  members 
of  the  Association  to  test  them.  Before  a  method  can  be  adopted  as  O.Ticial,  it 
must  have  been  tested  through  cooperative  work  and  must  have  been  recommended 
by  the  appropriate  referee  for  at  least  two  years.  Official  Methods,  therefore, 
are  those  which  have  been  thoroughly  tested  and  which,  in  the  opinion  of  the  Associa- 
tion, yield  accurate  results  in  the  hands  of  its  members.  In  other  words,  they  are 
believed  to  render  as  absolutely  correct  results  as  are  possible  in  the  existing  state 
of  knowledge  concerning  the  determination  in  question.  Provisional  Methods 
are  those  which,  while  in  the  opinion  of  the  Association  yielding  dependable  results 
for  comparison,  have  not  as  yet  been  tested  so  thoroughly  as  those  that  have  been 
adopted  officially.  They  are  believed  to  be  the  best  of  the  kind  which  have  been 
tested  by  the  Association  but  which  for  reasons  stated  have  not  the  standing  of 
Official  Methods. 

The  methods  in  the  form  last  promulgated  by  the  Association,  either  in  Bulletin 
107  (Revised)  or  as  published  in  their  Proceedings  of  the  last  eight  years,  are  as 
yet  the  only  ones  adopted  by  the  Association. 

It  should  be  clearly  understood  that  the  revised  methods  as  published  herewith 
are  simjjly  the  report  of  the  Committee  on  Editing  Methods  of  Analysis,  including 
the  recommendations  adopted  at  the  1915  meeting,  and  at  the  present  time  have  not 
been  officially  adopted.  The  methods  are  printed  at  this  time  to  enable  the  mem- 
bers of  the  Association  to  study  and  criticize  them  so  that  they  may  be  able  to  vote 
on  them  intelligently  at  the  1916  meeting  at  which  time  the  matter  will  come  up 
for  final  action. 


RECOMMENDATIONS  FOR  OFFICIAL  AND  TENTATIVE 
METHODS  OF  ANALYSIS,  AS  PRESENTED  AT 
THE  ANNUAL  MEETING  OF  THE  ASSO- 
CIATION OF  OFFICIAL  AGRICUL- 
TURAL CHEMISTS,  NOVEMBER 
16  AND  17,  1915. 

I.     FERTILIZERS. 

GENERAL  METHODS. 

1  MECHANICAL  ANALYSIS  OF  BONE  AND  TANKAGE.— TENTATIVE. 

Transfer  100  grams  of  the  original  material  to  a  sieve  having  circular  openings 
1/50  inch  (0.5  mm.)  in  diameter.  Sift,  breaking  the  lumps  by  means  of  a  soft  rubber 
pestle  if  the  material  has  a  tendency  to  cake.  Weigh  the  coarse  portion  remaining 
on  the  sieve.     Determine  the  fine  portion  by  difference. 

2  PREPARATION  OF  SAMPLE.— OFFICIAL. 

Reduce  the  gross  sample  by  quartering  to  an  amount  sufficient  for  analytical 
purposes.  Transfer  to  a  sieve  having  circular  openings  1/25  inch  (1  mm.)  in  diameter, 
sift,  breaking  the  lumps  with  a  soft  rubber  pestle.  Grind  in  a  mortar  the  part  re- 
maining on  the  sieve  until  the  particles  will  pass  through.  Mi.\  thoroughly  and 
preserve  in  tightly  stoppered  bottles.  Grind  and  sift  as  rapidly  as  possible  to 
avoid  loss  or  gain  of  moisture  during  the  operation. 


Note:  p. 59-154  (as  vol.2,  no. 2,  part  1.  Aug.  15,  1916  of 
the  Journal  of  the  Association  of  Official  Agricultural 
■-^:,  Chemists)  were  first  published  as  vol.2,  no.l,  part  2, 

^         May  15,  1916,  incorrectly  paged  1-96. 


«i 


t  REAGENTS. 

(a)  Molybdate  solution. — Dissolve  100  grams  of  molybdic  acid  in  dilute  ammo- 
nium hydroxid  (144  cc.  of  ammonium  hydroxid  (sp.  gr.  0.90)  and  271  cc.  of  water); 
pour  this  solution  slowly  and  with  constant  stirring  into  dilute  nitric  acid  (4S9  cc.  of 
nitric  acid  (sp.  gr.  1.42)  and  IMS  cc.  of  water).  Keep  the  mixture  in  a  warm  place 
for  several  days  or  until  a  portion  heated  to  40°C.  deposits  no  yellow  precipitate 
of  ammonium  phosphomolybdate.  Decant  the  solution  from  any  sediment  and 
preserve  in  glass-stoppered  vessels. 

(b)  Ammonium  nitrate  sohition. — Dissolve  200  grams  of  commercial  ammonium 
nitrate,  phosphate  free,  in  water  and  dilute  to  2  liters. 

(C)  Magnesia  mixture. — Dissolve  22  grams  of  recently  ignited  calcined  magnesia 
in  dilute  hydrochloric  acid,  avoiding  an  excess  of  the  latter.  Add  a  little  calcined 
magnesia  in  excess,  and  boil  a  few  minutes  to  precipitate  iron,  aluminium,  and  phos- 

1 


RECOMMENDATIONS  FOR  OFFICIAL  AND  TENTATIVE 
METHODS  OF  ANALYSIS,  AS  PRESENTED  AT 
THE  ANNUAL  MEETING  OF  THE  ASSO- 
CIATION OF  OFFICIAL  AGRICUL- 
TURAL CHEMISTS,  NOVEMBER 
16  AND  17,  1915. 

I.     FERTILIZERS. 

GENERAL  METHODS. 

1  MECHANICAL  ANALYSIS  OF  BONE  AND  TANKAGE.-TENTATIVE. 
Transfer  100  grams  of  the  original  material  to  a  sieve  having  circular  openings 

1/50  inch  (0.5  mm.)  in  diameter.  Sift,  breaking  the  lumps  by  means  of  a  soft  rubber 
pestle  if  the  material  has  a  tendency  to  cake.  Weigh  the  coarse  portion  remaining 
on  the  sieve.     Determine  the  fine  portion  by  difference. 

2  PREPARATION  OF  SAMPLE.— OFFICIAL. 

Reduce  the  gross  sample  by  quartering  to  an  amount  sufficient  for  analytical 
purposes.  Transfer  to  a  sieve  having  circular  openings  1/25  inch  (1  mm.)  in  diameter, 
sift,  breaking  the  lumps  with  a  soft  rubber  pestle.  Grind  in  a  mortar  the  part  re- 
maining on  the  sieve  until  the  particles  will  pass  through.  Mix  thoroughly  and 
preserve  in  tightly  stoppered  bottles.  Grind  and  sift  as  rapidly  as  possible  to 
avoid  loss  or  gain  of  moisture  during  the  operation. 

3  MOISTURE.— OFFICIAL. 

Heat  2  grams  of  the  sample  prepared  as  in  2  for  5  hours  in  a  water  oven  at  the 
temperature  of  boiling  water.  In  the  case  of  potash  salts,  sodium  nitrate,  and 
ammonium  sulphate  heat  at  about  130°C.  to  constant  weight.  The  loss  in  weight 
is  considered  as  moisture. 

TOTAL  PHOSPHORIC  ACID. 

Gravimetric  Method. — Official. 

4  REAGENTS. 

(a)  Molybdate  solution. — Dissolve  100  grams  of  molybdic  acid  in  dilute  ammo- 
nium hydroxid  (141  cc.  of  ammonium  hydroxid  (sp.  gr.  0.90)  and  271  cc.  of  water); 
pour  this  solution  slowly  and  with  constant  stirring  into  dilute  nitric  acid  (4S9  cc.  of 
nitric  acid  (sp.  gr.  1.42)  and  IMS  cc.  of  water).  Keep  the  mixture  in  a  warm  place 
for  several  days  or  until  a  portion  heated  to  40°C.  deposits  no  yellow  precipitate 
of  ammonium  phosphomolybdate.  Decant  the  solution  from  any  sediment  and 
preserve  in  glass-stoppered  vessels. 

(b)  Ammonium  nitrate  solution. — Dissolve  200  grams  of  commercial  ammonium 
nitrate,  phosphate  free,  in  water  and  dilute  to  2  liters. 

(C)  Magnesia  mixture. — Dissolve  22  grams  of  recently  ignited  calcined  magnesia 
in  dilute  hydrochloric  acic|,  avoiding  an  excess  of  the  latter.  Add  a  little  calcined 
magnesia  in  excess,  and  boil  a  few  minutes  to  precipitate  iron,  aluminium,  and  phos- 

1 


2  METHODS    OF   ANALYSIS  [Chap. 

phoricacid;  filter;  add  280  grams  of  ammonium  chlorid,  2G1  cc.  of  ammonium  liydrox- 
id  (sp.  gr.  0.90)  and  dilute  to  2  liters.  Instead  of  the  solution  of  22  grams  of  cal- 
cined magnesia,  110  grams  of  crystallized  magnesium  chlorid  (MgCUGIIiiO)  dissolved 
in  water  may  be  used,  then  add  280  grams  of  ammonium  chlorid  and  proceed  as  above. 

(d)  Dilute  ammonium  hydroxid  for  washing. — Dilute  100  cc.  of  ammonium  hy- 
droxid  (sp.  gr.  0.90)  to  1  liter. 

(e)  Magnesium  nitrate  solution. — Dissolve  320  grams  of  calcined  magnesia  in 
nitric  acid,  avoiding  an  excess  of  the  latter;  then  add  a  little  calcined  magnesia  in 
excess,  boil,  filter  from  the  excess  of  magnesia,  ferric  oxid,  etc.,  and  dilute  to  2  liters. 

5  PREPAJIATION   OF  SOLUTION. 

Treair  2  or  2.5  gi-ams  of  the  sample  by  one  of  the  methods  given  below: 

(a)  Ignite",  and  di.ssolve  in  hydrochloric  acid. 

.(b)-Evaponite.' with  5  cc.  of  magnesium  nitrate,  ignite,  and  dissolve  in  hydro- 
chtoric  aci'd;  -  •      '  - 

(C)  Boil  with  20-30  cc.  of  strong  sulphuric  acid  in  a  Kjeldahl  flask,  adding  2-4 
grams  of  sodium  or  potassium  nitrate  at  the  beginning  of  the  digestion  and  a  small 
quantity  after  the  solution  has  become  nearly  colorless,  or  adding  the  nitrate  in 
small  portions  from  time  to  time.  After  the  solution  is  colorless  add  150  cc.  of  water, 
and  boil  for  a  few  minutes. 

(d)  Digest  in  a  Kjeldahl  flask  with  strong  sulphuric  acid  and  such  other  re- 
agents as  are  used  in  either  the  plain  or  modified  Kjeldahl  or  Gunning  method  for 
estimating  nitrogen.  Do  not  add  any  potassium  permanganate,  but  after  the 
solution  has  become  colorless  add  about  100  cc.  of  water  and  boil  for  a  few  minutes. 

(e)  Dissolve  in  30  cc.  of  concentrated  nitric  acid  and  a  small  quantity  of  hydro- 
chloric acid  and  boil  until  organic  matter  is  destroyed. 

(f)  Add  30  cc.  of  concentrated  hydrochloric  acid,  heat  and  add  cautiously,  in 
small  quantities  at  a  time,  about  0.5  gram  of  finely  pulverized  potassium  chlorate 
to  destroy  organic  matter. 

(g)  Dissolve  in  15-30  cc.  of  strong  hydrochloric  acid  and  3-10  cc.  of  nitric  acid. 
This  method  is  recommended  for  fertilizers  containing  much  iron  or  aluminium 
phosphate. 

After  solution,  cool,  dilute  to  200  cc.  or  to  250  cc.  if  a  2.5  gram  sample  was  used. 
Mix,  and  pour  on  a  dry  filter. 

6  DETERMINATION. 

Take  an  aliquot  of  the  solution  prepared  as  directed  above,  corresponding  to  0.25 
gram,  0.50  gram,  or  1  gram,  neutralize  with  ammonium  hydroxid,  and  clear  with  a 
few  drops  of  nitric  acid.  In  case  hydrochloric  or  sulphuric  acid  has  been  used  as 
a  solvent,  add  about  15  grams  of  dr}'  ammonium  nitrate  or  a  solution  containing 
that  amount.  To  the  hot  solution  add  60-80  cc.  of  the  molybdate  solution  for  every 
decigram  of  phosphoric  acid  (P2O5)  that  is  present.  Digest  at  about  65°C.  for  an 
hour,  and  determine  if  the  phosphoric  acid  has  been  completely  precipitated  by 
the  addition  of  more  molybdate  solution  to  the  clear  supernatant  liquid.  Fil- 
ter and  wash  with  cold  water  or,  preferably,  ammonium  nitrate  solution.  Dissolve 
the  precipitate  on  the  filter  with  ammonium  hydroxid  and  hot  water  and  wash 
into  a  beaker  to  a  bulk  of  not  more  than  100  cc.  Nearly  neutralize  with  hydrochloric 
acid,  cool,  and  add  magnesia  mixture  from  a  burette;  add  slowly  (about  1  drop  per 
second),  stirring  vigorously.  After  15  minutes  add  12  cc.  of  ammonium  hydroxid 
(sp.  gr.  0.90).  Let  stand  till  the  supernatant  liquid  is  clear  (2  hours  is  usually 
enough)  filter,  wash  with  the  dilute  ammonium  hydroxid  until  the  washings  are 


I]  FERTILIZERS  3 

practically  free  from  chlorin,  dry  the  filter  and  precipitate  and  transfer  the  latter 
to  a  weighed  porcelain  crucible.  Ignite  the  filter  separately  and  add  its  ash  to  the 
precipitate  in  the  crucible.  Ignite  to  whiteness  or  to  a  grayish  white,  weigh,  and 
calculate  to  phosphoric  acid  (P2O5). 

Volumetric  Method. — Official. 

7  REAGENTS. 

(a)  Molyhdate  solution. — To  100  cc.  of  molybdate  solution  prepared  as  directed 
in  4  (a),  add  5  cc.  of  nitric  acid  (sp.  gr.  1.42).  This  solution  should  be  filtered  im- 
mediately before  using. 

(b)  Standard  sodium  or  potassium  hydroxid  solution. — Dilute  323.81  cc.  of  N/1 
alkali,  free  from  carbonates,  to  1  liter.  100  cc.  of  the  solution  should  neutralize 
32.38  cc.  of  N/1  acid;  1  cc.  is  equivalent  to  1  mg.  of  P2O5  (1%  of  F2O5  on  a  basis  of 
0.1  gram  of  substance). 

(C)  Standard  acid  solution. — Prepare  an  acid  solution  corresponding  to  the, 
or  to  one-half  of  the,  strength  of  (b),  and  standardize  by  titration  against  that 
solution,  using  phenolphthalein  as  indicator.  Hydrochloric  or  nitric  acid  may  be 
used. 

(d)  Phenolphthalein  solution. — Dissolve  1  gram  of  phenolphthalein  in  100  cc.  of 
alcohol. 

8  PREPARATION   OF   SOLUTION. 

Dissolve  according  to  5  (b),  (e),  (f),  or  (g),  preferably  by  (e),  when  these  acids 
are  a  suitable  solvent,  and  dilute  to  200  cc.  with  water. 

9  DETERMINATION. 

(a)  For  percentages  of  5  or  below  use  an  aliqifot  corresponding  to  0.4  gram  of 
substance,  for  percentages  between  5  and  20  use  an  aliquot  corresponding  to  0.2 
gram  of  substance,  and  for  percentages  above  20  use  an  aliquot  corresponding  to 
0.1  gram  of  substance.  Add  5-10  cc.  of  nitric  acid,  depending  on  the  method  of 
solution  (or  the  equivalent  in  ammonium  nitrate),  nearly  neutralize  with  ammonium 
hydroxid,  dilute  to  75-100  cc,  heat  in  a  water  bath  to  60°-65°C.,  and  for  percentages 
below  5  add  20-25  cc.  of  freshly  filtered  molybdate  solution.  For  percentages  be- 
tween 5  and  20  add  30-35  cc.  of  molybdate  solution.  For  percentages  greater  than 
20  add  sufficient  molybdate  solution  to  insure  complete  precipitation.  Stir,  let 
stand  in  the  bath  about  15  minutes,  filter  at  once,  wash  once  or  twice  with  water  by 
decantation,  using  25-30  cc.  each  time,  agitate  the  precipitate  thoroughly  and 
allow  to  settle;  transfer  to  the  filter  and  wash  with  cold  water  until  the  filtrate  from 
2  fillings  of  the  filter  yields  a  pink  color  upon  the  addition  of  phenolphthalein  and  1 
drop  of  the  standard  alkali.  Transfer  the  precipitate  and  filter  to  a  beaker  or  pre- 
cipitating vessel,  dissolve  the  precipitate  in  a  small  excess  of  the  standard  alkali, 
add  a  few  drops  of  phenolphthalein  solution,  and  titrate  with  the  standard  acid. 

(b)  Proceed  as  in  (a)  with  this  exception:  Heat  in  a  water  bath  at  45°-50''C., 
add  the  molybdate  solution,  and  allow  to  remain  in  the  bath  with  occasional  stirring 
for  30  minutes. 

(C)  Proceed  as  in  (a)  to  the  point  where  the  solution  is  ready  to  place  in  the 
water  bath.  Then  cool  the  solution  to  room  temperature,  add  molybdate  solution 
at  the  rate  of  75  cc.  for  each  decigram  of  phosphoric  acid  present,  place  the  stoppered 
flask  containing  the  solution  in  a  shaking  apparatus  and  shake  for  30  minutes  at 
room  temperature,  filter  at  once,  wash,  and  titrate  as  in  (a). 


4  METHODS    OF   ANALYSIS  [Chap. 

WATER-SOLUBLE  PHOSPHORIC  ACID. 

10  Gravimelric  Method. — Official. 

Place  2  grams  of  the  sample  on  a  9  cm.  filter,  wash  with  successive  small  portions 
of  water,  allowing  each  portion  to  pass  through  before  adding  more,  until  the  filtrate 
measures  about  250  cc.  If  the  filtrate  is  turbid,  add  a  little  nitric  acid.  Make  up 
to  any  convenient  volume,  mix  well,  use  an  aliquot,  and  proceed  as  under  6. 

1 1  Volumetric  Method. — Official. 

Treat  the  sample  as  directed  under  10.  To  an  aliquot  of  the  solution  cor- 
responding to  0.2  or  0.4  gram,  add  10  cc.  of  concentrated  nitric  acid  and  ammonium 
hydroxid  until  a  slight  permanent  precipitate  is  formed,  dilute  to  60  cc,  and  pro- 
ceed as  directed  under  9. 

CITRATE-INSOLUBLE  PHOSPHORIC  ACID.— OFFICIAL. 

12  REAGENTS. 

In  addition  to  the  reagents  given  under  4  and  7  prepare  ammonium  citrate  solu- 
tion by  one  of  the  following  methods: 

Ammonium  citrate  solution. — (1)  Dissolve  370  grams  of  commercial  citric  acid 
in  1500  cc.  of  water;  nearly  neutralize  with  commercial  ammonium  hydroxid;  cool; 
add  ammonium  hydroxid  until  exactly  neutral  (testing  with  litmus  or  azolitmin 
paper),  and  dilute  sufficiently  to  make  the  specific  gravity  1.09  at  20°C.  The  vol- 
ume will  be  about  2  liters;- or, 

(2)  To  370  grams  of  commercial  citric  acid  add  commercial  ammonium  hydroxid 
until  nearly  neutral;  reduce  the  specific  gravity  to  slightly  more  than  1.09  at  20°C. 
and  make  exactly  neutral,  testing  as  follows:  Prepare  a  solution  of  fused  calcium 
chlorid,  200  grams  to  the  liter,  and  add  4  volumes  of  strong  alcohol.  Make  this 
solution  exactly  neutral,  using  a  small  amount  of  freshly  prepared  corallin  solution 
as  preliminary  indicator,  and  test  finally  by  withdrawing  a  portion,  diluting  with 
an  equal  volume  of  water,  and  testing  with  cochineal  solution;  50  cc.  of  this  solution 
will  precipitate  the  citric  acid  from  10  cc.  of  the  citrate  solution.  To  10  cc.  of  the 
nearly  neutral  citrate  solution  add  50  cc.  of  the  alcoholic  calcium  chlorid  solution, 
stir  well,  filter  at  once  through  a  folded  filter,  dilute  with  an  equal  volume  of 
water,  and  test  the  reaction  with  neutral  solution  of  cochineal.  If  acid  or  alkaline, 
add  ammonium  hydroxid  or  citric  acid,  as  the  case  may  be,  to  the  citrate  solution, 
mix,  and  test  again,  as  before.  Repeat  this  process  until  a  neutral  reaction  is 
obtained.     Add  sufficient  water  to  make  the  specific  gravity  1.09  at  20°C. 

13  DETERMINATION. 

(a)  Acidulated  samples. — Heat  100  cc.  of  strictly  neutral  ammonium  citrate 
solution  (sp.  gr.  1.09)  to  65°C.  in  a  250  cc.  Erlenmeyer  flask  placed  in  a  warm  water 
bath,  keeping  the  flask  loosely  stoppered  to  prevent  evaporation.  The  level  of  the 
water  in  the  bath  should  be  above  that  of  the  citrate  solution  in  the  flask.  When 
the  citrate  solution  has  reached  65°C.,  drop  into  it  the  filter  containing  the  washed 
residue  from  the  water-soluble  phosphoric  acid  solution  in  1 0,  close  tightly  with 
a  smooth  rubber  stopper,  and  shake  violently  until  the  filter  paper  is  reduced  to 
a  pulp,  relieving  the  pressure  by  momentarily  removing  the  stopper.  Place  the 
flask  in  the  bath  and  maintain  its  contents  at  exactly  65°C.  Shake  the  flask  every 
5  minutes.  At  the  expiration  of  exactly  30  minutes  from  the  time  the  filter  and  the 
residue  are  introduced,  remove  the  flask  from  the  bath  and  immediately  filter  the 
contents  as  rapidly  as  possible   through  a  quick-acting  filter  paper.     Wash  with 


I]  FERTILIZERS  5 

water  at  65°C.  until  the  volume  of  the  filtrate  is  about  350  cc,  allowing  time  for 
thorough  draining  before  adding  new  portions  of  water.  (1)  Transfer  the  filter 
and  its  contents  to  a  crucible,  ignite  until  all  organic  matter  is  destroyed,  add  10- 
15  cc.  of  strong  hydrochloric  acid,  and  digest  until  all  phosphate  is  dissolved;  or, 
(2)  Return  the  filter  with  contents  to  the  digestion  flask,  add  30-35  cc.  of  strong 
nitric  acid,  5-10  cc.  of  strong  hydrochloric  acid,  and  boil  until  all  phosphate  is  dis- 
solved. Dilute  the  solution  as  prepared  in  (1)  or  (2)  to  200  cc.  If  desired,  the  filter 
and  its  contents  may  be  treated  according  to  methods  5  (b),  (C)  or  (d).  Mix  well, 
filter  through  a  dry  filter  and  proceed  as  directed  under  6  or  9. 

(b)  Non-acidulated  samples. — In  case  a  determination  of  citrate-insoluble  phos- 
phoric acid  is  required  in  non-acidulat«d  samples  treat  2  grams  of  the  phosphatic 
material  without  previous  washing  with  water,  precisely  as  in  (a),  except  when  the 
substance  contains  much  animal  matter  (bone,  fish,  etc.),  in  which  case  dissolve 
the  residue  insoluble  in  ammonium  citrate  by  any  one  of  the  processes  described 
under  5  (b),  (C)  or  (d)  and  determine  phosphoric  acid  as  directed  in  6  or  9. 

14  CITRATE-SOLUBLE  PHOSPHORIC  ACID.— OFFICL&L. 

The  sum  of  the  water-soluble  and  citrate-insoluble  subtracted  from  the  total 
gives  the  citrate-soluble  phosphoric  acid. 

15  DETECTION  OF  NITRATES.— OFFICIAL. 

Mix  5  grams  of  the  fertilizer  with  25  cc.  of  hot  water  and  filter.  To  a  portion  of 
this  solution  add  2  volumes  of  concentrated  sulphuric  acid,  free  from  nitric  acid  and 
oxids  of  nitrogen,  and  allow  the  mixture  to  cool.  Add  cautiously  a  few  drops  of  a 
concentrated  solution  of  ferrous  sulphate  so  that  the  fluids  do  not  mix.  If  nitrates 
are  present  the  junction  shows  at  first  a  purple,  afterwards  a  brown,  color  or  if  only 
a  very  minute  quantity  be  present,  a  reddish  color.  To  another  portion  of  the  solu- 
tion add  1  cc.  of  a  1%  solution  of  sodium  nitrate  and  test  as  before  to  determine 
whether  sufficient  sulphuric  acid  were  added  in  the  first  test. 

ORGANIC  AND  AMMONIACAL  NITROGEN  ONLY. 

Kjddahl  Method.— Official. 

1 6  REAGENTS. 

For  ordinary  work  N/2  acid  is  recommended.  For  work  in  determining  very 
small  amounts  of  nitrogen  N/10  acid  is  recommended.  In  titrating  mineral  acids 
against  ammonium  hydroxid  solution  use  cochineal  or  methyl  red  as  indicator. 

(a)  Standard  hydrochloric  acid. — Determine  the  absolute  strength  as  follows: 
Preliminarij  test. — Place  a  measured  portion  of  the  acid  to  be  standardized  in  an 
Erlenmeyer  flask  with  excess  of  calcium  carbonate,  to  neutralize  free  acid,  and  a 
few  drops  of  potassium  chromate  as  indicator.  By  titration  with  silver  nitrate 
solution  determine  exactly  the  quantity  required  to  precipitate  the  chlorin.  Final 
determination. — To  a  measured  portion  of  the  acid  to  be  standardized  add  from  the 
burette  1  drop  in  excess  of  the  required  quantity  of  silver  nitrate  solution  as  deter- 
mined by  the  preceding  test.  Heat  to  boiling,  protect  from  the  light,  and  allow  to 
stand  until  the  precipitate  is  granular.  Filter  on  a  tared  Gooch  crucible,  previously 
heated  to  140°-150°C..  wash  with  hot  water,  testing  the  filtrate  to  prove  excess  of 
silver  nitrate.     Dry  the  silver  chlorid  at  140°-150°C.,  cool  and  weigh. 

(b)  Standard  sulphuric  oczcZ.— Determine  the  absolute  strength  of  the  acid  by 
precipitation  with  barium  chlorid  solution  as  follows:  Dilute  a  measured  quantity 
of  the  acid  to  be  standardized  to  approximately  100  cc,  heat  to  boiling  and  add  drop 


6  METHODS    OF    ANALYSIS  [Chap. 

by  drop  a  10  %  solution  of  barium  chlorid  until  no  further  jjrccii^itation  occurs. 
Continue  the  boiling  for  about  5  minutes,  allow  to  stand  for  5  hours  or  longer  in  a 
warm  place,  pour  the  supernatant  liquid  on  a  tared  Gooch  or  on  an  ashless  filter, 
treat  the  precipitate  with  25-30  cc.  of  boiling  water,  transfer  to  the  filter  and  wash 
with  boiling  water  until  the  filtrate  is  free  from  chlorin.  Dry,  ignite  over  a  Bunsen 
burner  and  weigh  as  barium  sulphate. 

(C)  Standard  alkali  solution. — Accurately  determine  the  strength  of  this  solution 
by  titration  against  the  standard  acid.     N/10  solution  is  recommended. 

(d)  Sulphuric  acid. — Sp.  gr.  1.84  and  free  from  nitrates  and  ammonium  sulphate. 

(e)  Metallic  mercury,  or  mercuric  oxid. — Mercuric  oxid  should  be  prepared  in  the 
wet  way,  but  not  from  mercuric  nitrate. 

(f)  Copper  sulphate. — Crystallized. 

(^)  Potassium  permanganate. — Finely  pulverized. 

(h)  Granulated  zinc  or  pumice  stone. — Added  to  the  contents  of  the  distillation 
flask  if  necessary  to  prevent  bumping. 

(i)  Potassium  sulphid  solution. — Dissolve  40  grams  of  commercial  potassium 
sulphid  in  1  liter  of  water. 

(j )  Sodium  hydroxid  solution. — A  saturated  solution,  free  from  nitrates. 

(k)  Cochineal  solution. — Digest,  with  frequent  agitation,  3  grams  of  pulverized 
cochineal  in  a  mixture  of  50  cc.  of  strong  alcohol  and  200  cc.  of  water  for  1  or  2  days 
at  ordinary  temperature,  and  then  filter. 

(1)  Methyl  red  solution. — Dissolve  1  gram  of  methyl  red  (dimethyl-amino-azo- 
benzene-ortho-carbonic  acid)  in  100  cc.  of  95%  alcohol. 

17  APPARATUS. 

(a)  Kjeldahl  flasks  for  both  digestion  and  distillation. — Total  capacity  of  about 
550  cc,  made  of  hard,  moderately  thick,  and  well-annealed  glass. 

(b)  Distillation  flasks. — For  distillation  any  suitable  flask  of  about  550  cc.  capac- 
ity may  be  used.  It  is  fitted  with  a  rubber  stopper  through  which  passes  the  lower 
end  of  a  Kjeldahl  connecting  bulb  to  prevent  sodium  hydroxid  being  carried  over 
mechanically  during  distillation.  The  bulb  should  be  about  3  cm.  in  diameter,  and 
the  tubes  should  be  of  the  same  diameter  as  the  condenser  tube  with  which  the  upper 
end  of  the  bulb  tube  is  connected  by  means  of  rubber  tubing. 

1 8  DETERMINATION. 

Place  0.7-3.5  grams,  according  to  the  nitrogen  content,  of  the  substance  to  be 
analyzed  in  a  digestion  flask  with  approximately  0.7  gram  of  mercuric  oxid,  or  its 
equivalent  in  metallic  mercury,  and  add  20-30  cc.  of  sulphuric  acid  (0.1-0.3  gram  of 
crj'stallized  copper  sulphate  may  also  be  used  in  addition  to  the  mercur}-,  or  in 
place  of  it).  Place  the  flask  in  an  inclined  position  and  heat  below  the  boiling 
point  of  the  acid  until  frothing  has  ceased.  (A  small  piece  of  paraffin  may  be  added  to 
prevent  extreme  foaming.)  Then  raise  the  heat  until  the  acid  boils  briskly  and  digest 
for  a  time  after  the  mixture  is  colorless  or  nearly  so,  or  until  oxidation  is  complete. 
Remove  the  flask  from  the  flame,  hold  it  upright,  and  while  still  hot  add  care- 
fully potassium  permanganate  in  small  quantities  at  a  time  until,  after  shaking, 
the  liquid  remains  green  or  purple. 

After  cooling  dilute  with  about  200  cc.  of  water,  add  a  few  pieces  of  granulated 
zinc  or  pumice  stone,  if  necessary  to  prevent  bumping,  and  25  cc.  of  potassium  sul- 
phid solution  with  shaking.  Next  add  sufficient  sodium  hj^droxid  solution  to  make 
the  reaction  strongly  alkaline,  50  cc.  are  usually  enough,  pouring  it  down  the  side  of 
the  flask  so  that  it  does  not  mix  at  once  with  the  acid  solution.     Connect  the  flask 


IJ  FERTILIZERS 

with  the  condenser,  mix  the  contents  by  shaking,  distil  until  all  ammonia  has 

over  into  a  measured  quantity  of  the  standard  acid  and  titrate  with  the  standard 

alkali.     The  first  150  cc.  of  the  distillate  will  generally  contain  all  the  ammonia. 

The  use  of  mercuric  oxid  in  this  operation  greatly  shortens  the  time  necessary 
for  digestion,  which  is  rarely  over  an  hour  and  a  half  in  case  of  substances  most 
difficult  to  oxidize,  and  is  more  commonly  less  than  an  hour.  In  most  instances 
the  use  of  potassium  permanganate  is  quite  unnecessary,  but  it  is  believed  that  in 
exceptional  cases  it  is  required  for  complete  oxidation,  and  in  view  of  the  uncer- 
tainty it  is  always  used.  The  potassium  sulphid  removes  all  the  mercurj"-  from  the 
solution,  and  so  prevents  the  formation  of  mercuro-ammoniura  compounds  which 
are  not  completely  decomposed  by  the  sodium  hydroxid.  The  addition  of  zinc 
gives  rise  to  an  evolution  of  hydrogen  and  prevents  violent  bumping. 

Previous  to  use  the  reagents  should  be  tested  by  a  blank  experiment  with  sugar. 
The  sugar  partially  reduces  any  nitrates  present  that  might  otherwise  escape  notice. 

Gunning  Method. — Official. 

19  REAGENTS. 

Potassium  sulphate. — Pulverized. 

The  other  reagents  and  standard  solutions  used  are  described  under  16. 

20  APPARATUS. 

The  apparatus  used  is  described  under  17. 

21  DETERMINATION. 

Place  0.7-3.5  grams,  according  to  the  nitrogen  content,  of  the  substance  to  be 
analyzed  in  a  digestion  flask.  Add  10  grams  of  powdered  potassium  sulphate  and 
15-25  cc.  (ordinarily  about  20  cc.)  of  sulphuric  acid  (0.1-0.3  gram  of  crystallized 
copper  sulphate  may  also  be  added).  Conduct  the  digestion  as  in  the  Kjeldahl 
process,  starting  with  a  temperature  below  the  boiling  point  and  increasing  the  heat 
gradually  until  frothing  ceases.  Digest  for  a  time  after  the  mixture  is  colorless  or 
nearly  so,  or  until  oxidation  is  complete.  Do  not  add  either  potassium  permanganate 
or  potassium  sulphid.  Cool,  dilute,  neutralize,  distil,  and  titrate  with  the  standard 
alkali.  In  neutralizing  before  distilling  it  is  convenient  to  add  a  few  drops  of 
phenolphthalein  indicator  or  litmus  paper.  The  pink  color  given  by  phenolphthal- 
ein  indicating  an  alkaline  reaction  is  destroj-ed  by  a  considerable  excess  of  strong 
fixed  alkali. 

Kjeldahl-Gunning -Arnold  Method. — Official. 

22  REAGENTS  AND  APPARATUS. 

Described  under  16,  17  and  19. 


DETERMINATION. 


23 

Place  0.7-3.5  grams,  according  to  the  nitrogen  content,  of  the  substance  to  be 
analyzed  in  a  digestion  flask.  Add  15-18  grams  of  potassium  sulphate,  1  gram  of 
copper  sulphate,  1  gram  of  mercuric  oxid,  or  its  equivalent  in  metallic  mercury, 
and  25  cc.  of  sulphuric  acid.  Heat  gently  until  frothing  ceases,  then  boil  the  mixture 
briskly,  and  continue  the  digestion  for  a  time  after  the  mixture  is  colorless  or  nearly 
so  or  until  oxidation  is  complete.  Cool,  dilute  with  about  200  cc.  of  water,  add  50  cc. 
of  potassium  sulphid  sqlution,  make  strongly  alkaline  with  sodium  hydroxid  solu- 
tion and  complete  the  determination  as  directed  under  18. 


8  METHODS   OF  ANALYSIS  [Chap. 

TOTAL  NITROGEN. 
Kjeldahl  Method  Modified  to  include  the  Nitrogen  of  Nitrates. — Official. 

24  REAGENTS. 

(a)  Zinc  dust. — Impalpable  powder.  Granulated  zinc  or  zinc  filings  will  not 
answer. 

(b)  Sodiu7n  thiosulphate. 

(C)  Commercial  salicylic  acid. 

The  other  reagents  and  standard  solutions  are  described  under  16. 

25  APPARATUS. 

The  apparatus  used  is  described  under  1 7. 

26  DETERMINATION. 

Place  0.7-3.5  grams,  according  to  the  nitrogen  content,  of  the  substance  to  be 
analyzed  in  a  Kjeldahl  digestion  flask.     (1)  Add  30  cc.  of  sulphuric  acid  containing 

1  gram  of  salicylic  acid,  shake  until  thoroughly  mi.xed,  allow  to  stand  for  at  least 
.30  minutes,  and  then  add  5  grams  of  crystallized  sodium  thiosulphate  and  digest  as 
directed  below;  or,  (2)  Add  to  the  substance  30  cc.  of  sulphuric  acid  containing  2 
grams  of  salicylic  acid,  allow  to  stand  at  least  30  minutes  and  then  add  gradually 

2  grams  of  zinc  dust,  shaking  the  contents  of  the  flask  at  the  same  time  and  digest 
as  follows: 

Place  the  flask  on  the  stand  for  holding  the  digestion  flasks  and  heat  over  a  low 
flame  until  all  danger  from  frothing  has  passed.  Then  raise  the  heat  until  the  acid 
boils  briskly  and  continue  the  boiling  until  white  fumes  no  longer  escape  from  the 
flask.  This  requires  about  5-10  minutes.  Add  approximately  0.7  gram  of  mercuric 
oxid,  or  its  equivalent  in  metallic  mercury,  and  continue  the  boiling  until  the  liquid 
in  the  flask  is  colorless,  or  nearly  so.  In  case  the  contents  of  the  flask  are  likely  to 
become  solid  before  this  point  is  reached,  add  10  cc.  more  of  sulphuric  acid.  Complete 
the  oxidation  with  a  little  potassium  permanganate  in  the  usual  way  and  proceed 
as  directed  under  18.     The  reagents  should  be  tested  by  blank  experiments. 

Gunning  Method  Modified  to  include  the  Nitrogen  of  Nitrates. — Official. 

27  REAGENTS  AND  APPARATUS. 

The  reagents  and  standard  solutions  are  described  under  16,  17,  19  and  24. 

28  DETERMINATION. 

Place  0.7-3.5  grams,  according  to  the  nitrogen  content,  of  the  substance  to  be 
analj^zed  in  a  digestion  flask.  Add  30-35  cc.  of  salicylic  acid  mixture  (30  cc.  of  sul- 
phuric acid  to  1  gram  of  salicylic  acid) ;  shake  until  thoroughly  mixed,  and  allow  to 
stand  for  at  least  30  minutes  with  frequent  shaking.  Add  5  grams  of  sodium  thio- 
sulphate and  heat  the  solution  for  5 minutes;  cool;  add  10  grams  of  potassium  sulphate 
and  heat  very  gently  until  foaming  ceases,  then  strongly  until  nearly  colorless, 
and  proceed  as  directed  under  21 . 


Absolute  or  Cupric  Oxid  Method. — Official. 

29  REAGENTS. 

(a)  Coarse  cupric  oxid. — Ignite  and  cool  before  using. 

(b)  Fine  cupric  oxid. — Grind  (a). 


FERTILIZERS 


9 


(C)  Metallic  copper.— Granulated  copper,  or  fine  copper  gauze,  heated  and  cooled 
in  a  current  of  hydrogen  or  by  dropping  the  heated  copper  into  a  test  tube  containing 
a  few  cc.  of  methyl  alcohol. 

(d)  Sodium  hicarhonate. — Free  from  organic  matter. 

(e)  Caustic  potash  solution. — A  supersaturated  solution  of  caustic  potash  in  hot 
water. 

30  APPARATUS. 

(a)  Combustion  tube. — Hard  Bohemian  glass,  about  65  cm.  long,  12.7  mm.  internal 
diameter  and  sealed  at  one  end. 

(b)  Azotometer. — Capacity  100  cc,  accurately  calibrated. 
(C)  Sprengel  mercury  air  pump. 

(d)  Small  paper  scoop. — Made  from  stiff  writing  paper. 

31  DETERMINATION. 

Use  1-2  grams  of  ordinary  commercial  fertilizers.  In  the  case  of  highly  nitrogen- 
ized  substances,  the  amount  to  be  used  is  governed  by  the  amount  of  nitrogen  esti- 
mated to  be  present.     Fill  the  tube  (Fig.  1)  as  follows:  (1)  about  5  cm.  of  coarse 


y/. 


^SiE 


n^ 


I  \E  \m 


sg8ffl®®»3SgS8Bas&a@{^^^sg(ss 


>LJLiiJ 


5  CM.  10    CM. 

CQAR5E     SUBSTANCe 

OX  IV.      ANO  firiE  onto. 


T  CM.        6  cn 
MSTAUic  capiat 

COPPER.     OMD. 


2.5  cn 

FRSE    e  NO- 


SODIUM 
BICARBONATB. 


THE  ROMAN  NUMERALS  REFER  TO  THE  ORDER  IN  WHICH  THE  DIFFERENT 
PORTIONS  ARE  TO  BE  HEATED. 


cupric  oxid;  (2)  place  on  the  small  paper  scoop  a  sufficient  amount  of  the  fine  cupric 
oxid  which,  when  mixed  with  the  substance  to  be  analyzed,  will  fill  about  10  cm.  of 
the  tube;  pour  on  this  the  substance,  rinsing  the  watch  glass  with  a  little  of  the  fine 
oxid,  and  mix  thoroughly  with  a  spatula,  pour  into  the  tube,  rinsing  the  scoop  with 
a  little  fine  oxid;  (3)  about  30  cm.  of  coarse  cupric  oxid;  (4)  about  7  cm.  of  metallic 
copper;  (5)  about  6  cm.  of  coarse  cupric  oxid;  (6)  a  small  plug  of  asbestos;  (7)  0.8-1 
gram  of  sodium  bicarbonate;  (8)  a  large  loose  plug  of  asbestos. 

After  the  tube  is  filled  hold  in  a  horizontal  position  and  tap  gently  on  the  table 
in  order  that  a  canal  may  be  formed  in  the  upper  portion  of  the  fine  cupric  oxid. 
Place  the  tube  in  the  combustion  furnace,  leave  about  2.5  cm.  of  it  projecting  and 
connect  with  the  pump  by  a  rubber  stopper  smeared  with  glycerol,  taking  care  to 
make  the  connection  perfectly  tight.  In  order  to  protect  the  latter  from  the  heat, 
place  an  asbestos  plate,  having  a  circular  opening  in  the  center,  over  the  projecting 
end  of  the  tube. 

Exhaust  the  air  from  the  tube  by  means  of  the  pump.  When  a  vacuum  has  been 
obtained,  allow  the  flow  of  mercury  to  continue;  light  the  gas  under  that  part  of  the 


10  METHODS   OF  ANALYSIS  [Chap. 

tube  containing  the  metallic  copper,  the  anterior  layer  of  cupric  oxid  and  the  sodium 
bicarbonate.  As  soon  as  the  vacuum  is  destroyed  and  he  apparatus  filled  w  th 
carbon  dioxid,  shut  off  the  flow  of  mercury  and  at  once  introduce  the  delivery  tube 
of  the  pump  into  the  receiving  arm  of  the  azotometer  just  below  the  surface  of  the 
mercury  seal  so  that  the  escaping  bubbles  will  pass  into  the  air  and  not  into  the  tube, 
to  avoid  the  useless  saturation  of  the  caustic  potash  solution. 

When  the  flow  of  carbon  dioxid  has  very  nearly  or  completely  ceased,  pass  the 
delivery  tube  down  into  the  receiving  arm  so  that  the  bubbles  will  escape  into  the 
azotometer.  Light  the  gas  under  the  30  cm.  layer  of  oxid,  heat  gently  for  a  few 
minutes,  to  drive  out  anj^  moisture  that  may  be  present,  and  then  bring  to  a  red  heat. 
Heat  gradually  the  mixture  of  substance  and  oxid,  lighting  a  jet  at  a  time.  Avoid 
a  too  rapid  evolution  of  bubbles,  which  should  be  allowed  to  escape  at  the  rate 
of  about  one  per  second  or  a  little  faster.  When  the  burners  under  the  mixture  have 
all  been  turned  on,  light  the  gas  under  the  layer  of  oxid  at  the  end  of  the  tube. 
When  the  evolution  of  bubbles  has  ceased,  turn  out  all  the  burners  except  those 
under  the  metallic  copper  and  anterior  layer  of  oxid,  and  allow  to  cool  for  a  few  min- 
utes. Exhaust  with  the  pump  and  remove  the  azotometer  before  the  flow  of  mercury 
has  stopped.  Break  the  connection  of  the  tube  with  the  pump,  stop  the  flow  of 
mercury,  and  extinguish  the  burners.  Allow  the  azotometer  to  stand  for  at  least 
an  hour,  or  cool  with  a  stream  of  water  until  the  volume  and  temperature  become 
constant. 

Adjust  accurately  the  level  of  the  potassium  hydroxid  solution  in  the  bulb  to 
that  in  the  azotometer;  note  the  volume  of  the  nitrogen,  temperature,  and  height  of 
barometer;  calculate  the  weight  of  the  nitrogen  as  usual. 

AMMONIACAL  NITROGEN. 

32  Magnesium  Oxid  Method. — Official. 

Place  0.7-3.5  grams,  according  to  the  ammonia  content,  of  the  substance  to  be 
analj'zed  in  a  distillation  flask  with  about  200  cc.  of  water  and  5  grams  or  more  of 
magnesium  oxid,  free  from  carbonates.  Then  connect  the  flask  with  a  condenser  and 
distil  100  cc.  of  the  liquid  into  a  measured  quantity  of  standard  acid  and  titrate 
with  standard  alkali  solution. 

NITRIC  AND  AMMONIACAL  NITROGEN. 

33  Ulsch-Slreet  Method.— Official. 

Place  1  gram  of  the  sample  in  a  half-liter  flask,  add  about  30  cc.  of  water  and  2-3 
grams  of  reduced  iron,  and,  after  standing  sufficiently  long  to  insure  solution  of  the 
soluble  nitrates  and  ammonium  salts,  add  10  cc.  of  a  mixture  of  strong  sulphuric  acid 
with  an  equal  volume  of  water;  shake  thoroughl}',  place  a  long-stemmed  funnel  in  the 
neck  of  the  flask  to  prevent  mechanical  loss,  and  allow  to  stand  for  a  short  time  until 
the  violence  of  the  reaction  has  moderated.  Heat  the  solution  slowly,  boil  for  5 
minutes,  and  cool.  Add  about  100  cc.  of  water,  a  little  paraffin,  and  7-10  grams  of 
magnesium  oxid,  free  or  nearly  free  from  carbonates.  Connect  with  a  condenser, 
such  as  is  used  in  the  Kjeldahl  method,  and  boil  the  mixture  for  40  minutes,  nearly 
to  dryness;  collect  the  ammonia  in  a  measured  quantity  of  standard  acid,  and  titrate 
with  standard  alkali  solution  in  the  usual  manner.  The  nitrogen  obtained  represents 
the  nitrates  plus  the  ammonium  salts  contained  in  the  sample. 

In  the  analysis  of  nitrate  salts  proceed  as  above,  except  that  25  cc.  of  the  nitrate 
solution,  equivalent  to  0.25  gram  of  the  sample,  are  emplo3^ed  with  5  grams  of  re- 
duced iron.  After  boiling  add  75  cc.  of  water  and  an  excess  of  sodium  hydroxid 
solution  and  complete  the  determination  as  above. 


I]  FERTILIZERS  11 

34  Zinc-Iron  Method. — Official. 

Dissolve  10  grams  of  the  sample  in  water  and  dilute  to  500  cc.  Place  25  cc.  of 
this  solution,  corresponding  to  0.5  gram  of  the  substance,  in  a  400  cc.  distillation  flask, 
add  120  cc.  of  water,  5  grams  of  well-washed  and  dried  zinc  dust,  and  5  grams  of 
reduced  iron.  To  the  solution  add  80  cc.  of  saturated  sodium  hydroxid  solution, 
connect  the  flask  with  the  condensing  apparatus  and  conduct  the  distillation  .simul- 
taneously with  the  reduction,  collecting  the  ammonia  in  standard  acid.  Continue 
the  distillation  until  100  cc.  have  been  distilled  and  titrate  with  standard  alkali 
solution. 

NITROGEN  IN  NITRATE  SALTS. 

35  Ferrous  Sulphate-Zinc-Soda  Method. — Tentative. 

Place  0.5  gram  of  the  nitrate  salt  in  a  600-700  cc.  flask,  add  200  cc.  of  water, 
5  grams  of  powdered  zinc,  1-2  grams  of  ferrous  sulphate,  and  50  cc.  of  sodium  hy- 
droxid solution  (36°  Baume).  Connect  with  the  distilling  apparatus,  distil,  collect 
the  distillate  in  the  usual  way  in  N/10  sulphuric  acid  and  titrate  with  standard 
alkali  solution. 

ORGANIC   NITROGEN  SOLUBLE  IN  NEUTRAL  PERMANGANATE.— OFFICIAL. 

36  Preliminary  Test  {Determination  of  Water-Insoluble  Organic  Nitrogen). 

Place  1  gram  of  the  material  on  an  11  cm.  filter  paper  and  wash  with  water  at 
room  temperature  until  the  filtrate  measures  250  cc.  Dry  and  determine  nitrogen 
in  the  residue,  as  in  18  or  21,  making  a  correction  for  the  nitrogen  of  the  filter, 
if  necessary. 

37  DETERMINATION. 

Place  a  quantity  of  the  fertilizer,  equivalent  to  50  mg.  of  water-insoluble  organic 
nitrogen  as  determined  in  36,  on  a  moistened  11  cm.  filter  paper  and  wash  with  water 
at  room  temperature  until  the  filtrate  measures  250  cc.  Transfer  the  insoluble 
residue  with  25  cc.  of  tepid  water  to  a  300  cc.  Griffin  low-form  beaker,  add  1  gram 
of  sodium  carbonate,  mix,  and  add  100  cc.  of  2%  permanganate.  Cover  with  a 
watch  glass  and  immerse  for  30  minutes  in  a  steam  or  hot  water  bath  so  that  the  level 
of  the  liquid  in  the  beaker  is  below  that  of  the  water  in  the  bath.  Stir  twice  at  inter- 
vals of  10  minutes.  At  the  end  of  the  digestion  remove  from  the  bath,  add  immedi- 
ately 100  cc.  of  cold  water,  and  filter  through  a  heavy  15  cm.  folded  filter.  Wash 
with  small  quantities  of  cold  water  until  the  filtrate  measures  about  400  cc.  De- 
termine nitrogen  in  the  residue  and  filter,  as  in  18  or  21,  correcting  for  the  nitrogen 
contained  in  the  latter.  The  nitrogen  thus  obtained  is  the  inactive  water-insoluble 
organic  nitrogen.  Subtract  this  result  from  that  obtained  in  36  to  obtain  the 
percentage  of  organic  nitrogen  soluble  in  neutral  permanganate. 

ORGANIC  NITROGEN  SOLUBLE  IN  ALKALINE  PERMANGANATE.— OFFICIAL. 
(Not  applicable  to  fertilizers  containing  cottonseed  meal  or  castor  pomace.) 

38  PREPARATION  OF  SAMPLE. 

(a)  Mixed  fertilizers. — Place  an  amount  of  material,  equivalent  to  50  mg.  of  water- 
insoluble  organic  nitrogen  determined  as  directed  under  36,  on  a  filter  paper  and 
wash  with  water  at  room  temperature  until  the  filtrate  measures  250  cc. 


12  METHODS    OF   ANALYSIS  (Chap. 

(b)  Raw  materials. — Place  an  amount  of  material,  equivalent  to  50  mg.  of  water- 
insoluble  organic  nitrogen  determined  as  directed  under  36,  in  a  small  mortar,  add 
about  2  grams  of  powdered  rock  phosphate,  mix  thoroughly,  transfer  to  a  filter  paper, 
and  wash  with  water  at  room  temperature  until  the  filtrate  measures  250  cc. 
When  much  oil  or  fat  is  present,  it  is  well  to  wash  with  ether  before  extracting  with 
water. 

39  DETERMINATION. 

Dry  the  residue  of  38  at  a  temperature  not  exceeding  80°C.  and  transfer  from  the 
filter  to  a  500-600  cc.  Kjeldahl  distillation  flask.  Add  20  cc.  of  water,  15-20  small 
glass  beads,  or  fragments  of  pumice  stone,  a  piece  of  paraffin  the  size  of  a  pea,  and 
100  cc.  of  alkaline  permanganate  solution  (25  grams  of  pure  potassium  permanganate 
and  150  grams  of  sodium  hydroxid,  separately  dissolved  in  water,  the  solutions  cooled, 
mixed,  and  made  to  a  volume  of  1  liter).  Connect  with  an  upright  condenser  to 
the  lower  end  of  which  a  receiver  containing  standard  acid  has  been  attached. 
Digest  slowly,  for  at  least  30  minutes,  below  distillation  point,  with  a  very  low  flame, 
using  coarse  wire  gauze  and  asbestos  paper  between  the  flask  and  flame.  Gradually 
raise  the  temperature  and,  after  any  danger  from  frothing  has  passed,  distil  until 
95  cc.  of  the  distillate  are  obtained,  and  titrate  as  usual.  When  a  tendency  to  froth 
is  noticed,  lengthen  the  digestion  period  and  no  trouble  will  be  experienced  when  the 
distillation  is  begun.  During  the  digestion  gently  rotate  the  flask  occasionally, 
particularly  if  the  material  shows  a  tendency  to  adhere  to  the  sides.  The  nitrogen 
thus  obtained  is  the  active  water-insoluble  organic  nitrogen. 


Method  I. 
Lindo-Gladding  Method. — Official. 

40  REAGENTS. 

(a)  Ammonium  chlorid  solution. — Dissolve  100  grams  of  ammonium  chlorid  in 
500  cc.  of  water,  add  5-10  grams  of  pulverized  potassium-platinic  chlorid,  and  shake 
at  intervals  for  6-8  hours.  Allow  the  mixture  to  settle  overnight  and  filter.  The 
residue  may  be  used  for  the  preparation  of  a  fresh  supply. 

(b)  Platinum  solution.— A.  platinic  chlorid  solution  containing  the  equivalent  of 
1  gram  of  metallic  platinum  (2.1  grams  of  H2PtCl6)  in  every  10  cc. 

(C)  80%  alcohol.— Sp.  gr.  0.8645  at  -^^.  Denatured  alcohol,  made  up  according 
to  formula  1  (U.  S.  Internal  Rev.,  Reg.  No.  30,  Revised,  Aug.  22,  1911,  p.  45)  and  di- 
luted with  water  to  make  80%  alcohol  by  volume,  may  also  be  used. 

41  PREPARATION  OP  SOLUTION. 

(a)  Mixed  fertilizers.— Tlace  2.5  grams  of  the  sample  upon  a  12.5  cm.  filter  paper 
and  wash  with  boiling  water  until  the  filtrate  amounts  to  about  200  cc.  Add  to  the 
filtrate  2  cc.  of  concentrated  hydrochloric  acid,  heat  to  boiling,  transfer  to  a  250  cc. 
graduated  flask  and  add  to  the  hot  solution  a  slight  excess  of  ammonium  hj-droxid 
and  sufficient  ammonium  oxalate  to  precipitate  all  the  lime  present,  cool,  dilute  to 
250  cc,  mix,  and  pass  through  a  dry  filter. 

(b)  Potash  salts;  jnuriate  and  sulphate  of  potash,  sulphate  of  potash  and  magnesia, 
and  kainit. — Dissolve  2.5  grams  and  dilute  to  250  cc.  without  the  addition  of  am- 
monium hydroxid  and  ammonium  oxalate. 

(C)  Organic  compounds.— W^hen  it  is  desired  to  determine  the  total  amount  of 
potash  in  organic  substances,  such  as  cottonseed  meal,  tobacco  stems,  etc.,  saturate 


I]  FERTILIZERS  13 

10  grams  of  the  sample  with  strong  sulphuric  acid  and  ignite  in  a  muffle  at  a  low  red 
heat  to  destroy  organic  matter.  Add  a  little  strong  hydrochloric  acid,  warm  slightly 
in  order  to  loosen  the  mass  rom  the  dish,  transfer  to  a  250  cc.  graduated  flask,  add 
ammonia  and  ammonium  oxalate  and  proceed  as  in  (a). 

42  DETERMINATION. 

(a)  Mixed  fertilizers. — Evaporate  50  cc.  of  the  solution  in  41  (a)  nearly  to  dryness, 
add  1  cc.  of  dilute  sulphuric  acid  (1  to  1),  evaporate  to  dryness,  and  ignite  to  white- 
ness. Maintain  a  full  red  heat  until  the  residue  is  perfectly  white.  Dissolve  the 
residue  in  hot  water,  using  at  least  20  cc.  for  each  decigram  of  potassium  oxid  pres- 
ent, add  a  few  drops  of  hydrochloric  acid,  and  platinum  solution  in  excess.  Evap- 
orate on  a  water  bath  to  a  thick  paste.  Treat  the  residue  with  80%  alcohol,  avoid- 
ing exposure  to  ammonia.  Filter,  wash  the  precipitate  thoroughly  with  80%  alco- 
hol both  by  decantation  and  on  the  filter,  continuing  the  washing  after  the  filtrate 
is  colorless.  Then  wash  with  10  cc.  of  the  ammonium  chlorid  solution  to  remove 
impurities  from  the  precipitate  and  repeat  5  or  6  times.  Wash  again  thoroughly 
with  80%  alcohol  and  dry  the  precipitate  for  30  minutes  at  lOO'C.  Weigh  and  cal- 
culate to  potassium  oxid.     The  precipitate  should  be  perfectly  soluble  in  water. 

(b)  Muriate  of  potash. — Acidify  50  cc.  of  the  solution  prepared  according  to  41 
(b)  with  a  few  drops  of  hydrochloric  acid,  add  10  cc.  of  platinum  solution  and  evapo- 
rate to  a  thick  paste.     Treat  the  residue  as  under  (a). 

(C)  Sulphate  of  potash;  sulphate  of  potash  and  magnesia;  andkainit. — Acidify 
50  cc.  of  the  solution  prepared  according  to  41  (b)  with  a  few  drops  of  hydrochloric 
acid  and  add  15  cc.  of  platinum  solution.  Evaporate  the  mixture  and  proceed  as 
directed  under  (a),  except  that  25  cc.  portions  of  the  ammonium  chlorid  solution 
should  be  used. 

(d)  Water-soluble  potash  in  wood  ashes  and  cotton  hull  ashes. — Prepare  the  solution 
according  to  41  (a)  and  proceed  as  directed  under  (a), paying  special  attention  to 
the  last  sentence. 

Method  II.— Official. 
(The  Lindo-Gladding  method  is  preferable  in  the  presence  of  soluble  sulphates.) 

43  REAGENTS. 

Described  under  40. 

44  PREPARATION   OF  SOLUTION. 

Prepare  the  solution  as  directed  under  41,  omitting  in  all  cases  the  addition  of 
ammonium  hydroxid  and  ammonium  oxalate. 


DETERMINATION. 


45 

Dilute  25  cc.  of  the  solution  made  as  directed  under  44  (50  cc.  if  less  than  10% 
of  potassium  oxid  be  present)  to  150  cc,  heat  to  100°C.,  and  add,  drop  by  drop,  with 
constant  stirring,  a  slight  excess  of  barium  chlorid  solution.  Without  filtering,  add 
in  the  same  manner  barium  hydroxid  solution  in  slight  excess.  Filter  while  hot  and 
wash  until  the  precipitate  is  free  from  chlorin.  Add  to  the  filtrate  1  cc.  of  strong 
ammonium  hydroxid,  and  then  a  saturated  solution  of  ammonium  carbonate  until 
the  excess  of  barium  is  precipitated.  Heat  and  add,  in  fine  powder,  0.5  gram  of 
pure  oxalic  acid  or  0.75  gram  of  ammonium  oxalate.  Filter,  wash  free  from  chlorin, 
evaporate  the  filtrate  to  di'yness  in  a  platinum  dish,  and  ignite  carefully  over  the  free 


14  METHODS    OF   ANALYSIS  [Chap. 

flame,  below  a  red  heat,  until  all  volatile  matter  is  driven  off.  Digest  the  residue 
with  hot  water,  filter  through  a  small  filter  and  dilute  the  filtrate,  if  necessary,  so 
that  for  each  decigram  of  potassium  oxid  there  will  be  at  least  20  cc.  of  liquid.  Acid- 
ify with  a  few  drops  of  hydrochloric  acid  and  add  platinum  solution  in  excess.  Evap- 
orate on  a  water  bath  to  a  thick  paste  and  treat  the  residue  with  80%  alcohol,  both  by 
decantation  and  after  collecting  on  a  Gooch  or  other  form  of  filter,  dry  for  30  minutes 
at  100°C.  and  weigh.  If  there  is  an  appearance  of  foreign  matter  in  the  double  salt, 
it  should  be  washed  as  in  42  (a)  with  several  portions  of  10  cc.  each  of  the 
ammonium  chlorid  solution. 

THOMAS  OR  BASIC  SLAG.— TENTATIVE. 

46  MECHANICAL  ANALYSIS. 
Proceed  as  directed  under  1,  using  10  grams  of  material. 

47  PREPARATION   OF  SAMPLE. 
Prepare  the  sample  as  directed  under  2. 

TOTAL  PHOSPHORIC  ACID. 
Gravimetric  Method. 

48  PREPARATION   OF   SOLUTION. 

Prepare  the  solution  for  analysis  as  directed  under  5  (C),  or  in  strong  hydrochloric 
acid  alone.  In  the  latter  case  after  the  portion  for  analysis  is  measured  out,  add 
nitric  acid  and  heat  for  a  few  minutes. 

49  DETERMINATION. 

Dehydrate  an  aliquot  (20  cc.)  of  48  by  evaporating  to  dryness  on  a  steam  or  hot 
water  bath;  treat  with  5  cc.  of  hydrochloric  acid  and  25  cc.  of  hot  water;  digest  in 
order  to  complete  solution  and  filter  off  silica.  From  this  point  proceed  as  directed 
under  6.    Before  precipitating  with  magnesia  mixture,  add  5  cc.  of  5%  sodium  acetate. 

50  Volumetric  Method. 

Prepare  the  solution  as  directed  under  5  (C)  and  determine  the  phosphoric  acid 
in  an  aliquot  of  this  solution  as  directed  under  9,  standardizing  the  solutions 
against  a  standard  phosphate  material  of  approximately  the  same  composition 
as  the  sample  under  examination. 

CITRATE-SOLUBLE  PHOSPHORIC  ACID. 

Gravimetric  Method. — {Wagner's  Method.) 

51  PREPARATION   OF   SOLUTION. 

Weigh  5  grams  of  the  slag  into  a  500  cc.  Wagner  flask  containing  5  cc.  of  95% 
alcohol.  (The  flask  should  have  a  neck  width  of  at  least  22  mm.  and  should  be 
marked  at  least  S  cm.  below  the  mouth.)  Make  up  to  the  mark  with  2%  citric  acid 
solution  of  a  temperature  of  17.5°C.  Fit  the  flask  with  a  rubber  stopper  and  place 
at  once  in  a  rotary  apparatus,  shaking  the  flask  for  30  minutes  at  the  rate  of  30-40 
revolutions  per  minute,  at  the  end  of  which  time  remove  the  flask,  filter  immediately 
on  a  dry  filter  and  analyze  the  solution  at  once. 


I]  FERTILIZERS  16 

52  DETERMINATION. 

To  50  cc.  of  the  clear  filtrate  in  a  beaker  add  100  cc.  of  molybdate  solution  prepared 
as  directed  under  4  (a).  Place  the  beaker  in  a  water  bath,  until  the  temperature 
of  the  beaker's  contents  reaches  65 °C.,  remove  from  the  bath  and  cool  to  room  tem- 
perature. Filter  and  wash  the  yellow  precipitate  of  ammonium  phosphomolybdate 
4  or  5  times  with  1%  nitric  acid.  Dissolve  the  precipitate  in  100  cc.  of  cold  2% 
ammonium  hydroxid,  nearly  neutralize  with  hydrochloric  acid  and  add  to  the  solu- 
tion, drop  by  drop,  with  continuous  stirring,  15  cc.  of  magnesia  mixture  prepared  as 
directed  under  4  (C)  and  proceed  as  under  6. 

53  Volumetric  Method. 

In  an  aliquot  of  the  clear  solution  prepared  as  in  51,  determine  the  phosphoric 
acid  as  directed  under  9. 


II.    SOILS. 

1  DIRECTIONS  FOR  TAKING  SAMPLES.— OFFICIAL. 

Sampling  should  be  done  preferably  when  the  soil  is  reasonably  dry.  Remove 
from  the  surface  all  vegetable  material  not  incorporated  with  the  soil.  With  a  soil 
auger  or  tube,  whichever  may  be  better  adapted  to  the  soil  conditions,  take  a 
sufficient  number  of  sub-samples  at  properly  distributed  points  to  secure  composite 
samples  representative  of  the  entire  tract. 

(a)  Surface  soil. — Take  a  composite  sample  representative  of  the  entire  tract 
to  a  depth  of  either  (1)  6  inches,  (2)  the  average  depth  of  the  plowed  soil  if  this  ex- 
ceeds G  inches,  or  (3)  a  maximum  depth  of  12  inches  when  there  is  no  clear  line  of 
demarcation  between  the  soil  and  sub-soil  above  this  depth. 

(b)  Siih-soil.— Take  a  composite  sample  of  each  important  and  distinctly  different 
soil  stratum  below  the  surface  section  already  sampled  to  a  total  depth  of  40  inches. 
If  a  soil  auger  is  used,  before  taking  sub-soil  samples  the  hole  should  be  enlarged 
and  carefully  cleaned  out  with  the  auger  to  prevent  contamination  of  the  several 
substrata  when  the  sample  is  being  withdrawn. 

Mix  each  composite  sample  thoroughly  and,  after  cutting  down  by  quartering  to 
about  2-4  pounds,  air-dry  in  a  cool,  well-ventilated  place. 

It  is  recommended  that  the  weight  of  a  given  volume  of  the  soil  as  it  lies  in  the 
field  be  taken  for  calculating  the  percentage  results  obtained  by  analysis  to  pounds 
per  given  area  of  the  soil. 

2  PREPARATION  OF  SAMPLE. -OFFICIAL. 

After  air-drying  and  weighing  the  sample,  pulverize  in  a  porcelain  mortar,  using 
a  rubber-tipped  pestle  to  avoid  the  reduction  of  rock  fragments,  and  pass  through 
a  sieve  with  circular  openings  1/25  inch  (1  mm.)  in  diameter.  Discard  the  detritus 
and  weigh.  Thoroughly  mix  the  sifted  material  and  preserve  in  a  suitable  stoppered 
container. 

For  the  quantitative  determination  of  any  of  the  constituents,  prepare  a  very 
finely  pulverized  sub-sample  of  the  sifted  material,  using  an  agate  mortar. 

3  MOISTURE.— OFFICIAL. 

Dry  2  or  more  grams  of  the  sample,  as  prepared  under  2,  in  a  tared  platinum  dish 
for  5  hours  at  the  temperature  of  boiling  water;  cover  the  dish,  cool  in  a  desiccator, 
and  weigh  rapidly  to  prevent  the  absorption  of  moisture.  Heat,  cool,  and  weigh 
at  intervals  of  2  hours  to  constant  weight.     The  loss  of  weight  is  reported  as  moisture. 

4  VOLATILE  MATTER.-OFFICIAL. 

Heat  the  dish  and  dry  soil  from  3  to  full  redness,  stirring  occasionally, until  all  or- 
ganic matter  is  destro3'ed.  If  the  soil  contains  appreciable  quantities  of  carbonates, 
cool  and  moisten  with  a  few  drops  of  saturated  ammonium  carbonate  solution,  dry 
and  heat  to  dull  redness  to, expel  ammonium  salts;  cool  in  a  desiccator  and  weigh. 

17 


18 


METHODS   OF   ANALYSIS 


[Chap. 


ORGANIC  CARBON.— OFFICIAL. 

APPARATUS. 


(a)  A  calorimeter  bomb. — Use  a  type  that  permits  the  recovery  and  transfer  of  the 
entire  solid  residue  of  the  exploded  charge  to  a  small  vessel  by  means  of  a  jet  of 
water. 

(b)  Parr's  apparatus  for  determining  carbon  dioxide — Illustrated  in  Fig.  2. 


FIG,  2.    PARR'S  APPARATUS  FOR  THE  DETERMINATION  OF  CARBON  DIOXID. 


This  consists  of  a  150  cc.  Erlenmeyer  flask  {F)  fitted  with  a  3-holed  stopper  through 
2  of  which  the  stems  of  2  dropping  funnels  {S)  and  {A)  extend  almost  to  the  bottom 
of  the  flask.  A  capillary  tube,  passing  through  the  third  hole  and  flush  with  the 
bottom  of  the  stopper,  connects  with  the  gas  burette  {B). 

(C)  A  simple  Hemple  gas  pipette. — Contains  S0%  potassium  hydroxid  solution. 

6  DETERMIXATIOX. 

Introduce  2  grams  of  soil  as  prepared  under  2  (1  gram  if  high  in  organic  matter), 
0.75  gram  of  magnesium  powder,  and  10  grams  of  sodium  peroxid,  into  the  closed  dry 
calorimeter  bomb,  and  mix  thoroughly  by  shaking  the  bomb  back  and  forth.  Explode 
the  charge  by  means  of  an  electric  spark  or  by  dropping  a  red  hot  plug  into  the  bomb 
through  an  automatic  valve  which  closes  immediately  after  the  plug  enters.  Remove 
the  residue  from  the  bomb,  using  as  little  hot  water  as  possible,  heat  to  boiling,  and 
transfer  to  the  receiving  funnel  (S)  of  Parr's  apparatus.  From  the  acid  funnel  (A) 
run  50  cc.  of  sulphuric  acid  (1  to  2)  into  the  flask  (F).  Connect  the  apparatus  and 
slowly  add  the  contents  from  the  receiving  funnel  (S).  The  carbon  dioxid  gener- 
ated passes  through  the  capillary  tube  into  the  graduated  burette  (B).  Heat  the 
contents  of  the  flask  (F)  to  boiling  and  boil  for  1  minute,  then  force  the  gases  into 
the  graduated  burette  {B)  by  introducing  water  into  the  flask  (F)  through  the  fun- 
nel (S).  Read  the  burette,  recording  the  temperature  and  pressure.  Pass  the  gas 
into  an  ordinary  absorption  pipette  containing  30%  potassium  hydroxid  solution. 
Shake  the  gas  with  the  solution  until  carbon  dioxid  is  wholly  absorbed.     Return  the 


11] 


SOILS 


19 


residual  gas  to  the  graduated  burette  (B),  and  again  read  the  burette  noting  the 
temperature  and  pressure.  The  difference  in  readings  calculated  to  standard  con- 
ditions of  temperature  and  pressure  gives  the  number  of  cc.  of  carbon  dioxid  derived 
from  the  total  carbon  in  the  sample.  Conduct  a  blank  determination  upon  the 
reagents  used.  If  an  appreciable  amount  of  carbon  dio.xid  is  obtained  in  the  blank, 
the  result  expressed  in  terms  of  total  carbon  must  be  corrected  accordingly. 

Determine  the  inorganic  carbon  as  directed  under  9  and  subtract  it  from  the  total 
carbon  to  obtain  the  organic  carbon. 

INORGANIC   CARBON. 
Modified  Marr  Methods — Tentative. 

7  REAGENTS. 

(a)  N/IO  hydrochloric  acid. 

(b)  N/10  sodium  hydroxid. 

(C)  Dilute  hydrochloric  acid. — Dilute  25  cc.  of  concentrated  hydrochloric  acid 
(sp.  gr.  1.19)  to  250  cc.  with  carbon  dioxid-free  water. 

(d)  Barium  hydroxid  solution. — Prepare  a  saturated  aqueous  solution  of  barium 
hydroxid,  filter  through  asbestos  into  a  large  container  through  which  air  free 
from  carbon  dioxid  has  been  aspirated  for  some  time,  and  provide  an  arrangement 
whereby  the  solution  may  be  delivered  by  air  pressure  or  gravity  and  kept  from 
contact  with  carbon  dioxid  by  means  of  soda  lime  tubes. 

(e)  Carbon  dioxid-free  water. — Use  recently  boiled  and  cooled  water,  or  water 
from  which  carbon  dioxid  has  been  removed  by  aeration  for  a  sufficient  length  of 
time  with  carbon  dioxid-free  air.  Keep  in  a  container  provided  with  a  similar 
attachment  as  in  (d). 


8 


APPARATUS. 


HALF  FULL   OF 

BEADS  OR      . 

BROKEN  GLASS 


'iri 


■Lfl 


FIG.  3.    MODIFIED  MARR  APPAR^VTUS  FOR  DETERMINING  CARBON  DIOXID. 


The  apparatus  required  (Fig.  3),  consists  of  a  tube  {A),  50-60  cm.  long,  partly 
filled  with  beads  or  broken  glass  and  containing  strong  potassium  hydroxid  solution 
(1  to  2),  a  cylindrical  open  top  separatory  funnel  {B),  capacity  50  cc,  marked  at  20  and 
40  cc,  the  stem  of  which  extends  almost  to  the  bottom  of  the  250  cc.  fiask  (C)  into  the 


20  METHODS   OF  ANALYSIS  I  Chap. 

mouth  of  which  is  fitted,  by  means  of  a  rubber  stopper,  a  section  of  glass  tubing  10 
cm.  in  length  and  1  cm.  internal  diameter,  which  in  turn  is  furnished  with  a  side 
tube  extending  through  the  condenser  jacket  (D),  and  connected  by  means  of  a  rub- 
ber stopper  to  the  small  trap  (K),  which  is  attached  to  the  Meyer  absorption  appara- 
tus (E)  as  shown  in  the  figure.  The  Meyer  absorption  apparatus  is  provided  with  2 
large  bulbs,  each  of  about  250  cc.  capacity,  and  10  smaller  connecting  bulbs,  each  of 
about  10  cc.  capacity.  The  connections  between  the  various  bulbs  should  have  an 
internal  diameter  of  8-10  mm.  A  perforated  rubber  stopper  carrying  2  short  pieces 
of  capillary  tubing  each  provided  with  rubber  tubing  and  pinch-cocks  (N  and  0) 
is  fitted  into  the  other  opening  of  the  Meyer  absorption  apparatus;  (jY)  is  for  the 
addition  of  reagents,  (0)  is  connected  to  the  vacuum  pump. 

All  parts  of  the  apparatus  must  be  capable  of  withstanding  a  vacuum  of  approxi- 
mately 70  cm.  and  be  perfectly  air  tight. 

9  DETERMINATION. 

Place  5-20  grams  of  soil  as  prepared  under  2  (depending  upon  the  carbonate  con- 
tent as  indicated  by  qualitative  examination)  in  the  flask  (C),  and  connect  up  the 
apparatus,  but  do  not  connect  {A)  to  (B).  Close  the  stop-cock  (G)  and  the  pnch- 
cock  (N) ;  open  the  pinch-cock  (0)  and  exhaust  the  apparatus  to  a  vacuum  of  ap- 
proximately 70  cm.  Close  the  pinch-cock  (0).  Connect  the  barium  hydroxid 
container  by  means  of  the  pinch-cock  (A^  and  rubber  tube;  open  the  pinch-co^k 
(N)  and  allow  sufficient  barium  hydroxid  solution  to  flow  into  the  Meyer  absorption 
apparatus  to  fill  3  or  4  of  the  small  bulbs;  close  the  pinch-cock  (A'');  substitute  the 
barium  hydroxid  container  by  the  carbon  dioxid-free  water  container;  open  the 
pinch-cock  (A'^)  and  add  sufficient  carbon  dioxid-free  water  to  fill  all  the  small  bulbs 
and  most  of  the  lower  large  bulb.  Through  the  separatory  funnel  (S),  add  80  cc.  of 
carbon  dioxid-free  water  to  the  sample  in  the  flask  (C),  avoiding  the  entrance  of  any 
air,  open  the  pinch-cock  (0)  and  heat  to  boiling,  protecting  the  flask  from  the  direct 
fiame  by  a  w^ire  gauze  with  an  asbestos  center.  Adjust  the  burner  so  that  2-3  min- 
utes are  required  for  the  contents  of  the  flask  to  reach  boiling  temperature  and  boil 
until  bubbles  no  longer  pass  through  the  Meyer  absorption  apparatus.  Then  close 
the  pinch-cock  (0),  and  run  into  the  flask  (C),  avoiding  the  entrance  of  any  air, 
20  cc.  of  the  dilute  hydrochloric  acid  through  the  separatory  funnel  which  is  then 
connected  with  the  tube  {A).  This  proportion  of  hydrochloric  acid  plus  the  80  cc.  of 
water  previously  added,  gives  an  acid  (2  to  100)  for  the  decomposition  of  carbonates. 
If  the  nature  of  the  soil  is  such  that  a  greater  strength  of  acid  is  considered  necessary, 
an  amount  of  acid  (3  to  100)  may  be  used  for  digesting  the  soil.  Shake  the  Meyer 
apparatus  (E)  gently,  so  that  the  liquid  in  the  lower  large  bulb  is  brought  into  con- 
tact with  the  gas  therein,  and  open  (0)  carefully,  but  do  not  allow-  more  than  a  few- 
bubbles  to  escape  before  shaking  again.  Repeat  the  operation  several  times  until 
bubbles  no  longer  pass  through  the  Mej^er  apparatus  (E)  when  (0)  is  opened.  Leave 
(0)  open,  and  continue  the  boiling  for  about  25  minutes  until  carbon  dioxid  gas  is 
no  longer  evolved  from  the  sample  in  the  flask  (C).  Maintain  a  constant  flow  of 
cold  water  through  the  condenser  (D).  Do  not  allow  the  boiling  to  become  so  violent 
that  liquid  is  drawn  up  into  the  condenser  tube.  If  foaming  is  troublesome,  add  a 
drop  of  non-volatile  oil  through  the  separatory  funnel  (B).  When  the  evolution  of 
carbon  dioxid  has  ceased,  close  (0)  and  break  the  vacuum  by  cautiously  opening  the 
stop-cock  (G)  drawing  in  air  through  the  tube  (A). 

Disconnect  the  Mej^er  apparatus  (E)  and  filter  by  the  Cain  method^  as  follows: 
Prepare  a  filter  by  covering  a  perforated  porcelain  plate  within  a  carbon  funnel  with 
a  layer  of  asbestos,  and  a  laj'cr  of  ground  quartz,  both  of  which  have  previously  been 


II]  SOILS  21 

purified  by  digestion  with  hj'drochloric  acid  and  thorough  washing  with  water. 
The  filter  tube  passes  through  a  1-holed  rubber  stopper  which  fits  into  a  side  arm 
filtering  flask.  The  side  arm  of  this  flask  is  connected  to  the  suction  pipe  by  a  2-way 
stop-cock.  In  the  top  of  the  filter  tube  is  fitted  a  2-hoIcd  rubber  stopper  carrying 
glass  tubes  bent  at  right  angles.  To  these  tubes  are  attached  rubber  tubing  bearing 
pinch-cocks.  One  of  these  rubber  tubes  terminates  in  a  tube  containing  soda  lime. 
The  other  rubber  tube  is  connected  with  one  end  of  the  Meyer  apparatus.  The 
other  end  of  the  Meyer  apparatus  is  attached  to  a  bottle  containing  carbon 
dioxid-free  water  by  means  of  a  well-washed  rubber  tube  and  a  glass  tube  extending 
to  the  bottom  of  the  bottle.  This  glass  tube  passes  through  a  2-holed  rubber  stop- 
per. In  the  other  hole  of  the  stopper  is  placed  a  tube  containing  soda  lime.  A 
pinch-cock  is  placed  on  the  tube  joining  the  water  bottle  and  the  Meyer  apparatus. 
This  cock  is  kept  closed  until  the  precipitate  on  the  filter  is  ready  for  washing. 
With  the  pinch-cock  on  the  air  outlet  of  the  filter  tube  closed  and  the  pinch-cock 
from  the  filter  tube  to  the  Meyer  apparatus  open,  apply  gentle  suction  to  the 
filter  flask  until  the  contents  of  the  Meyer  apparatus  have  been  transferred  to  the 
filter.  When  necessary,  the  pinch-cock  to  the  air  inlet  of  the  filter  tube  is  opened 
to  admit  air  behind  the  liquid  in  the  Meyer  apparatus.  Open  the  pinch-cock  be- 
tween the  wash-water  bottle  and  the  Meyer  apparatus  and  open  the  stop-cock  lead- 
ing from  the  filter  flask  so  as  to  maintain  a  gentle  suction.  By  manipulation  of 
the  Meyer  apparatus  the  wash  water  comes  in  contact  with  all  parts  of  the  interior 
of  the  apparatus,  after  which  the  water  is  sucked  through  the  filter.  After  this 
thorough  washing  admit  air  through  the  side  opening  of  the  stop-cock  leading  to  the 
filter  flask. 

Disconnect  the  apparatus,  remove  the  filter  pad  with  the  barium  carbonate  from 
the  filter  tube  by  means  of  a  glass  rod,  place  in  a  beaker  and  add  a  measured  amount 
of  N/10  hydrochloric  acid  in  excess,  first  rinsing  the  Meyer  bulbs  with  a  small  amount, 
carefully  measured,  of  this  acid  and  water.  Titrate  the  excess  of  acid  with  N/10 
sodium  hydroxid,  using  methyl  orange  as  indicator.  Make  a  blank  determination 
under  the  same  conditions  and  apply  the  necessary  correction.  From  the  amount  of 
N/10  hydrochloric  acid  required  to  neutralize  the  barium  carbonate  formed  by  the 
carbon  dioxid  in  the  sample,  calculate  the  quantity  of  inorganic  carbon.  One  cc.  of 
N/10  acid  corresponds  to  0.0006  gram  of  carbon. 

10  TOTAL   NITROGEN.— OFFICIAL. 

Place  7-14  grams  of  the  soil,  as  prepared  under  2,  in  a  300  cc.  Kjeldahl  digestion 
flask  with  30  cc,  or  more  if  necessary,  of  concentrated  sulphuric  acid  and  0.7  gram  of 
mercuric  oxid,  or  0.65  gram  of  mercury.  Mix  immediately  by  shaking  to  prevent  the 
soil  from  adhering  to  the  sides  of  the  flask.  Heat  over  a  low  flame,  increase  the  heat 
gradually,  and  rotate  the  flask  frequently  or  shake  if  necessary  to  prevent  the  con- 
tents from  sticking  to  the  bottom  of  the  flask.  When  all  the  organic  matter  is  de- 
stroyed, continue  the  digestion  for  1  hour.  Oxidize  the  residue  with  potassium 
permanganate,  carefully  adding  small  portions  at  a  time  to  the  hot  liquid  until,  after 
shaking,  the  liquid  remains  green  or  purple.  After  cooling,  dilute  the  contents  of 
the  flask  with  100  cc.  of  water  and  transfer  to  a  700  cc.  copper  flask,  using  about  150  cc. 
of  water  to  wash  out  the  digestion  flask.  Add  an  excess  of  strong  alkali  solution 
containing  potassium  sulphid,  connect  the  flask  with  a  distilling  apparatus,  mix  the 
contents  thoroughly  and  complete  the  determination  as  directed  in  I,  18. 


22  METHODS   OF   ANALYSIS  [Chap. 

Strong  Acid  Digestion  of  the  Soil 

1 1  preparation  of  soil  solution.-official. 

Place  aa  amount  of  soil,  as  prepared  under  2  and  equivalent  to  10  grams  on  a  mois- 
ture-free basis,  in  a  200-300  cc.  non-soluble  glass  Erlenmeyer  flask  to  which  is  fitted,  by 
a  ground  joint  or  1-holed  rubber  stopper,  a  reflux  tube  20  inches  or  more  in  length. 
Add  lOOcc.of  hydrochloric  acid  of  constant  boiling  point  (approximate  sp.  gr.  1.115, 
1350  cc.  of  acid  (sp.  gr.  1.19),  and  1000  cc.  of  water),  and  digest  continuously 
for  10  hours  on  a  steam  or  water  bath,  shaking  the  flask  every  hour.  Allow  to  settle, 
and  avoiding  more  than  very  small  quantities  of  the  sediment,  decant  the  solution 
into  a  porcelain  dish  or  non-soluble  glass  beaker.  Transfer  by  means  of  hot  water 
the  insoluble  residue  to  a  filter,  wash  until  free  from  chlorin  and  add  the  washings 
to  the  original  solution.  Concentrate,  oxidize  the  organic  matter  present  in  the 
solution  with  a  few  drops  of  nitric  acid  and  evaporate  to  dryness  on  a  water  bath. 
Treat  with  hot  water,  add  a  few  cc.  of  hydrochloric  acid  and  again  evaporate  to  com- 
plete dryness.  When  the  final  evaporation  is  complete  and  the  dish  cooled,  moisten 
the  residue  with  a  few  drops  of  strong  hydrochloric  acid.  Add  10-20  cc.  of  water, 
warm  on  the  bath  to  secure  complete  solution  of  the  soluble  salts,  filter  and  wash 
until  free  from  chlorin.  Again  evaporate  the  solution  to  dryness  to  render  insoluble 
any  silica  that  may  remain  in  solution,  and  treat  as  above.  The  filtrate  constitutes 
the  acid  extract  freed  of  soluble  silica,  and  is  made  up  to  a  definite  volume  (250  or  500 
cc.)  and  designated  as  A. 

1 2  INSOLUBLE  RESIDUE.— OFFICIAL. 

Combine  the  filters  and  the  main  residue  obtained  in  11  in  a  small  dish,  dry,  ignite 
over  a  Bunsen  flame  for  an  hour  or  more,  carefully  at  first,  then  completely  over 
a  blast  lamp  to  constant  weight.  Weigh  and  calculate  as  the  insoluble  residue. 
This  residue  may  be  analyzed  by  the  usual  methods  applicable  to  silicates  or  it  may 
be  employed  in  the  determination  of  total  alkalies  as  described  under  26.  If  it  is 
desired  to  determine  the  silica  soluble  in  alkalies,  treat  a  separate  portion  of  the  soil 
as  directed  in  11,  except  that  all  filtrations  must  be  made  through  the  same  hard- 
ened filter,  then,  without  igniting,  wash  the  insoluble  residue  into  a  platinum  dish, 
dry  at  100°C.  and  complete  the  determination  as  directed  under  III,  4  (a). 

13  IRON,  ALUMINnrM  AND  PHOSPHORIC  ACID,  COLLECTIVELY.— OFFICIAL. 

(l)  To  an  aliquot  (50  or  100  cc,  according  to  the  probable  amount  of  iron 
present)  of  A,  under  11,  add  ammonium  hydroxid,  drop  by  drop,  until  the  precipi- 
tate formed  requires  several  seconds  to  dissolve,  thus  leaving  the  solution  but  faint- 
ly acid.  Heat  nearly  to  the  boiling  point,  and  add  ammonium  hydroxid  to  precipi- 
tate all  of  the  iron,  aluminium,  etc.  Boil  in  a  covered  beaker  for  about  1  minute, 
remove,  and  if  no  ammonia  is  given  off  (detected  by  smelling)  continue  the  addi- 
tion, drop  by  drop,  until  ammonia  can  be  detected.  Do  not  allow  the  precipitate 
to  settle,  but  stir  and  pour  on  the  filter.  Wash  immediately  with  hot  water,  using  a 
fine  jet  which  is  played  around  the  edge  of  the  precipitate,  thus  cutting  it  free 
from  the  paper  in  order  to  produce  rapid  filtration.  Wash  the  precipitate  several 
times,  return  it  to  the  original  beaker,  dissolve  with  a  few  drops  of  hydrochloric 
acid  and  warm.  Reprecipitate  the  iron,  aluminium  and  phosphoric  acid  with 
ammonium  hydroxid  as  above  and  wash  until  free  from  chlorin.  Designate  the 
filtrate  as  B. 

Dry  the  filter  and  precipitate,  remove  the  latter  from  the  filter,  ignite  the  filter 
separately  and  add  to  its  ash  the  precipitate.     Then  ignite  to  bright  redness,  cool 


II]  SOILS  23 

in  a  desiccator  and  weigh  as  ferric  oxid  (Fe203),  aluminium  oxid  (AUOs),  and  phos- 
phorus pentoxid  (P2O5).  Transfer  this  residue  to  a  flask,  digest  with  several  cc. 
of  sulphuric  acid  (1  to  4),  and  heat  to  accelerate  solution.  When  solution  is  complete 
reduce  with  zinc  and  determine  the  ferrous  iron  by  titration  with  a  standard  per- 
manganate solution,  and  calculate  to  ferric  oxid;  or,  (2)  In  lieu  of  the  above,  evapo- 
rate 50  or  lOOcc.of  A,  underll,  with  the  addition  of  10  cc.  of  su  phuric  acid  until  all 
hydrochloric  acid  is  expelled,  dilute  with  water,  reduce  with  zinc  and  determine  the 
ferrous  iron  by  titration  with  a  standard  permanganate  solution  and  calculate  to 
ferric  oxid. 

The  weight  of  ferric  oxid,  plus  that  of  the  phosphorus  pentoxid,  determined 
under  17  or  19,  subtracted  from  the  collective  weight  of  ferric  oxid,  aluminium 
oxid,  and  phosphorus  pentoxid,  gives  the  weight  of  the  aluminium  oxid. 

1 4  MANGANESE.— OFFICIAL. 

Concentrate  B,  under  13,  to  about  50  cc,  cool,  add  bromin  water  until  the  solution 
is  colored,  make  alkaline  with  ammonium  hydroxid,  and  heat  to  boiling  in  a  covered 
beaker;  cool,  and  repeat  the  addition  of  bromin  water,  of  ammonium  hydroxid  and 
boil  again.  If  a  precipitate  is  obtained,  slightly  acidify  the  solution  with  acetic 
acid,  filter  immediately,  and  wash  with  hot  water.  Dry  the  precipitate,  ignite  and 
weigh  as  manganomanganic  oxid  (MnsO^).  Designate  the  filtrate,  or  if  there  is  no 
precipitate,  the  original  solution,  as  C. 

1  5  CALCIUM.— OFFICIAL. 

Concentrate  C,  under  14,  to  about  50  cc,  make  slightly  alkaline  with  ammonium 
hydroxid,  and  add,  while  still  hot,  ammonium  oxalate  solution,  drop  by  drop,  slightly 
in  excess  of  complete  precipitation,  to  convert  the  magnesium  also  into  oxalate. 
Heat  to  boiling,  allow  the  precipitate  to  settle  completely,  decant  the  clear  solution 
on  a  filter,  pour  1.5-20  cc.  of  hot  w^ater  on  the  precipitate,  and  again  decant  the  clear 
solution  on  the  filter.  Dissolve  the  precipitate  in  the  beaker  with  a  few  drops  of 
hj'drochloric  acid,  add  a  little  water,  repeat  the  precipitation  as  above,  and  filter 
through  the  same  filter;  transfer  the  precipitate  to  the  filter  and  wash  free  from  chlo- 
rin  with  hot  water;  dry,  ignite  the  precipitate  over  the  blast  lamp  to  constant  weight, 
and  weigh  as  calcium  oxid.     Designate  the  filtrate  and  washings  as  D. 

1 6  MAGNESIUM.— OFFICIAL. 

Evaporate  D,  under  15,  to  dryness  on  the  water  bath  and  heat  carefully  to  expel 
ammonium  salts.  Treat  the  residue  with  20-25  cc.  of  hot  water  and  about  5  cc.  of 
hydrochloric  acid,  filter  and  wash.  Concentrate  to  about  50  cc,  cool,  and  add  suffi- 
cient disodium  hydrogen  phosphate  solution  to  precipitate  the  magnesium;  then 
add  gradually  ammonium  hydroxid,  with  constant  stirring,  until  the  solution  is 
distinctly  alkaline.  Determine  if  the  precipitation  is  complete  by  the  addition  of 
more  of  the  disodium  hydrogen  phosphate  solution.  After  30  minutes,  add  gradually 
10  cc.  of  strong  ammonium  hydroxid,  cover  to  prevent  the  escape  of  ammonia,  and 
let  stand  in  the  cold.  Filter  after  12  hours,  wash  the  precipitate  free  from  chlorin, 
using  dilute  ammonium  hvdroxid  [I,  4  (d)],  dry  the  filter  and  precipitate  and  trans- 
fer the  latter  to  a  weighed  porcelain  crucible.  Ignite  the  filter  separately  and  add 
its  ash  to  the  precipitate  in  the  crucible.  Burn  at  first  at  a  moderate  heat,  then 
ignite  to  whiteness  or  to  a  grayish  white,  weigh  as  magnesium  pyrophosphate 
(MgoPeO?)  and  calculate  to  magnesium  oxid  (MgO). 


24  METHODS    OF   ANALYSIS  [Chap. 

PHOSPHORIC  ACID. 

17  Gravimetric  Method. — Official. 

Concentrate  100-200  cc.  of  A,  under  11 ,  to  about  25-30  cc,  neutralize  with  ammo- 
nium hydroxid  and  add  about  10  cc.  additional.  Dissolve  the  precipitate  by  the  slow 
addition  of  dilute  nitric  acid,  stirring  constantly  and  avoiding  a  large  excess,  add 
gradually  about  20  cc.  of  molybdate  solution  [I,  4  (a)  ],  and  allow  to  stand  for  1  or  2 
hours  in  a  water  bath  at  a  temperature  of  40°C.  After  an  hour  determine  if  the 
precipitation  is  complete,  as  follows:  Pipette  about  5  cc.  of  the  clear  liquid  into  5  cc. 
of  warm  molybdate  solution.  If  any  precipitate  is  produced,  return  the  test  liquid 
to  the  main  portion,  add  more  molybdate  solution,  and  repeat  the  operation  until 
all  the  phosphoric  acid  is  precipitated.  Then  allow  to  stand  for  several  hours  at 
room  temperature,  preferably  overnight.  Filter  off  the  ammonium  phosphomolyb- 
date,  wash  the  precipitate  thoroughly  with  cold  water,  dissolve  with  ammonium 
hydroxid,  and  determine  as  magnesium  pyrophosphate,  as  directed  under  I,  6  and 
calculate  to  phosphorus  pentoxid  (P2O5). 

Volumetric  Method. — Tentative. 

1 8  REAGENTS. 

(a)  Standard  sodium  or  potassium  hydroxid  solution. — Strength  such  that  1  cc. 
of  this  solution  is  equivalent  to  0.0005  gram  of  phosphorus  pentoxid  (P2O6). 

(b)  Standard  nitric  acid  solution. — Strength  same  as  the  standard  alkali  solution 
described  under  (a)  as  determined  by  titration,  using  phenolphthalein  as  indicator. 

19  DETERMINATION. 

Proceed  as  in  1 7  until  all  the  phosphoric  acid  is  precipitated  and  then  complete 
the  determination  in  the  following  manner: 

Allow  the  solution  containing  the  yellow  precipitate  to  stand  for  at  least  3  hours 
at  a  temperature  not  above  40°C.,  filter  on  a  small  filter  paper  or  on  a  Gooch  crucible 
and  wash  with  cold  water  until  the  filtrate  from  2  fillings  of  the  filter  yields  a  slight 
pink  color  on  the  addition  of  phenolphthalein  and  1  drop  of  the  standard  alkali. 
Return  the  filter  and  precipitate  to  the  same  beaker  used  for  precipitating  the 
phosphomolybdate,  dissolve  the  yellow  precipitate  in  the  standard  sodium  or  potas- 
sium hydroxid  solution,  add  a  few  drops  of  phenolphthalein  and  titrate  the  excess  of 
alkali  with  the  standard  acid.     Calculate  to  phosphorus  pentoxid  (PaOs). 

20  SULPHURIC  ACID.-OFFICIAL. 

Evaporate  100-200  cc.  of  A,  under  11 ,  nearly  to  dryness  on  a  water  bath  to  expel 
the  excess  of  acid,  add  50  cc.  of  water,  heat  to  boiling  and  add,  drop  by  drop,  10% 
barium  chlorid  solution  until  no  further  precipitation  occurs.  Continue  the  boiling 
for  about  5  minutes  and  allow  to  stand  for  5  hours  or  longer  in  a  warm  place.  Decant 
the  liquid  on  an  ashless  filter  or  tared  Gooch,  previously  heated,  treat  the  precipitate 
with  15-20  cc.  of  boiling  water,  transfer  to  the  filter  and  wash  free  from  chlorin  with 
boiling  water.  Dry  the  precipitate  and  filter,  ignite,  weigh  as  barium  sulphate  and 
calculate  to  sulphur  trioxid  (SO3). 

POTASSIUM  AND  SODIUM. 

21  Method  I.— Official. 

(1)  Treat  the  filtrate  from  20  with  ammonium  hydroxid  exactly  as  in  13. 
Evaporate  the  filtrate  and  washings  to  dryness,  heat  below  redness  until  ammo- 
nium salts  are  expelled,  dissolve  in  hot  water,  add  5  cc.of  barium  hydroxid  solution, 


II]  SOILS  25 

and  heat  to  boiling;  let  settle  for  a  few  minutes,  and  determine  if  the  precipitation 
is  complete  by  the  addition  of  barium  hydroxid  solution  to  a  little  of  the  clear  liquid. 
When  no  further  precipitate  is  produced,  filter  and  wash  thoroughly  with  hot  water. 
Heat  the  filtrate  to  boiling,  add  ammonium  hydroxid  and  ammonium  carbonate  to 
complete  the  precipitation  of  the  barium,  calcium,  etc.,  let  stand  a  short  time  on  the 
water  bath,  filter,  and  wash  the  precipitate  thoroughly  with  hot  water;  evaporate 
the  filtrate  and  washings  to  dryness,  expel  ammonium  salts  by  heating  below  red- 
ness, treat  with  a  little  hot  water,  add  a  few  drops  of  ammonium  hydroxid,  1  or  2 
drops  of  ammonium  carbonate,  and  a  few  drops  of  ammonium  oxalate;  let  stand 
a  few  minutes  on  the  water  bath,  set  aside  for  a  few  hours,  filter,  evaporate  to  complete 
dryness  on  the  water  bath,  and  heat  to  dull  redness  until  all  ammonium  salts  are 
expelled  and  the  residue  is  nearly  or  quite  white.  Dissolve  in  a  minimum  amount 
of  water,  filter  into  a  tared  platinum  dish,  add  a  few  drops  of  hydrochloric  acid,  evap- 
orate to  dryness  on  the  water  bath,  heat  to  dull  redness,  cool  in  a  desiccator,  and 
weigh  as  potassium  and  sodium  chlorids.  Repeat  the  heating  until  constant  weight 
is  obtained.  Dissolve  in  a  small  amount  of  water;  if  any  residue  remains,  the  sepa- 
ration must  be  repeated  until  the  residue  of  potassium  and  sodium  chlorids  is  entirely 
soluble.  Dissolve  the  residue  with  water,  add  an  excess  of  platinic  chlorid  solution 
[1,40  (b)],  proceed  as  directed  under  I,  45  and  calculate  to  potassium  oxid  (KjO);  or, 
(2)  Instead  of  the  foregoing,  evaporate  to  dryness  a  fresh  aliquot  of  A,  under  11, 
redissolve  in  water,  treat  directly  with  barium  hydroxid  solution,  and  from  this  point 
proceed  as  directed  above  in  (1). 

22  Method  II.— Tentative. 

Proceed  as  in  21  through  "let  stand  a  short  time  on  the  water  bath"  (the  point 
at  which  the  barium,  calcium,  etc.,  have  been  precipitated  with  ammonium  hydroxid 
and  ammonium  carbonate)  and  then  proceed  as  follows: 

Filter  into  a  beaker,  add  1  or  2  drops  of  hydrochloric  acid  and  1  cc.  of  ammonium 
sulphate  (75  grams  to  1  liter),  digest  several  hours  on  a  water  bath,  and  filter  into  a 
tared  platinum  dish.  Evaporate  to  dryness,  heat  to  full  redness,  add  1  gram  of 
powdered  ammonium  carbonate;  heat  to  expel  excess  of  ammonium  carbonate, 
cool,  and  weigh  the  sulphates  of  sodium  and  potassium.  Determine  potassium  as 
directed  under  I,  42  (a)  and  calculate  to  potassium  oxid  (K2O). 

TOTAL  PHOSPHORUS. 

23  Magnesium  Nitrate  Method. — Official. 

Place  5  grams  of  soil,  as  prepared  under  2,  in  a  porcelain  dish.  Moisten  with  5-7 
cc.  of  magnesium  nitrate  solution  [I,  4  (e)  ].  Dry  on  the  water  bath  and  burn  off 
the  organic  matter  at  low  redness.  Cool,  moisten  slightly  with  water,  add  10  cc.of 
concentrated  hydrochloric  acid,  and  digest  2  hours  on  the  water  bath,  keeping  the 
dish  covered  with  a  watch  glass  and  stirring  2  or  3  times  during  the  digestion.  Trans- 
fer to  a  250  cc.  graduated  flask,  cool,  fill  to  the  mark,  mix  well,  and  pass  through 
a  dry  folded  filter,  pouring  back  on  the  filter  until  the  filtrate  becomes  clear.  Pipette 
an  aliquot  corresponding  to  2  or  4  grams  of  the  soil,  depending  upon  the  amount 
of  phosphorus  present,  into  a  porcelain  dish,  evaporate  to  dryness,  treat  with  hydro- 
chloric acid  and  water,  filter,  and  wash;  the  combined  volume  should  not  exceed 
40  cc.  Make  alkaline  with  ammonium  hydroxid,  and  dissolve  the  precipitate  by 
the  slow  addition  of  concentrated  nitric  acid,  using  a  slight  excess.  Add  gradu- 
ally, while  shaking,  5-15  cc.  of  molybdate  solution  [I,  7  (a)  ].  Keep  the  solution 
at  40°-50°C.  for  an  hour^  let  stand  overnight  at  room  temperature,  filter,  and  wash 
well  with  cold  water.  Return  the  filter  and  precipitate  to  the  same  flask  and  deter- 
mine phosphorus  volumetrically,  as  directed  under  19. 


26  METHODS    OF   ANALYSIS  [Chap. 

24  Sodium  Peroxid  Method. — Official. 

Place  10  grams  of  sodium  peroxid  in  an  iron  or  porcelain  crucible  and  thoroughly 
mix  with  5  grams  of  the  soil  as  prepared  under  2.  If  the  soil  has  very  little  organic 
matter,  add  a  little  starch  to  hasten  the  action.  Heat  the  mixture  carefully  by 
applying  the  flame  of  a  Bunsen  burner  directly  upon  the  surface  of  the  charge  and 
the  sides  of  the  crucible  until  the  action  starts.  Cover  the  crucible  until  the  re- 
action is  over  and  keep  at  a  low  red  heat  for  15  minutes.  Do  not  allow  fusion  to 
take  place.  By  means  of  a  large  funnel  and  a  stream  of  hot  water,  wash  the  charge 
into  a  beaker,  acidify  with  hydrochloric  acid  and  boil.  Transfer  to  a  500  cc.  gradu- 
ated flask,  cool  and  fill  to  the  mark.  If  the  action  has  taken  place  properly  there 
should  be  no  undecomposed  soil  in  the  bottom  of  the  flask.  Allow  the  silica  to 
settle  and  draw  off  200  cc.  of  the  clear  solution. 

Precipitate  the  iron,  aluminium,  and  phosphorus  with  ammonium  hydroxid; 
filter,  wash  several  times  with  hot  water,  wash  the  precipitate  back  into  the  beaker 
with  a  stream  of  hot  water,  and  dissolve  the  precipitate  in  hot  hydrochloric  acid, 
pouring  the  acid  upon  the  filter  to  dissolve  any  precipitate  adhering  to  it.  Evapo- 
rate the  solution  and  washings  to  dryness  on  a  water  bath.  Treat  with  dilute  hy- 
drochloric acid,  heating  if  necessary,  and  remove  the  silica  by  filtration.  Con- 
centrate the  filtrate  and  washings  to  about  10  cc,  add  2  cc.  of  strong  nitric  acid, 
and  make  alkaline  with  ammonium  hydroxid.  Add  nitric  acid  very  slowly  and  with 
constant  stirring  until  the  solution  is  clear,  avoiding  an  excess.  Heat  at  40°-50°C. 
on  a  water  bath,  add  15  cc.  of  molybdate  solution,  [I,  7  (a)  ],  and  maintain  this  tem- 
perature for  1-2  hours.  Let  stand  overnight,  filter,  and  wash  free  from  acid  with 
0.1%  solution  of  ammonium  nitrate,  and,  finally,  once  or  twice  with  cold  water. 
Transfer  the  filter  and  precipitate  to  the  same  beaker  and  determine  phosphorus 
volumetrically  as  directed  under  19. 

25  TOTAL  POTASSroM.-OFFICIAL. 

Decompose  the  soil  by  the  J.  L.  Smith  method^  as  follows:  Triturate  gently 
0.5  or  1  gram  of  the  finely  ground  soil  with  1  gram  of  dry  ammonium  chlorid  in  a 
smooth  mortar,  then  add  8  parts  of  calcium  carbonate  and  mix  intimately.  Trans- 
fer the  mixture  to  a  platinum  crucible,  rinsing  the  mortar  with  a  little  calcium  car- 
bonate. Heat  the  crucible  gradually  until  fumes  of  ammonium  salts  no  longer 
appear,  and  continue  until  the  lower  Ihree-fourths  only  of  the  crucible  are  brought 
to  a  red  heat.  Maintain  this  temperature  40-60  minutes.  The  temperature  should 
be  sufficient  to  keep  the  calcium  chlorid  formed  by  the  reaction  of  ammonium  chlo- 
rid with  calcium  carbonate  in  a  state  of  fusion.  The  mass,  however,  does  not  be- 
come liquid  since  the  fused  calcium  chlorid  is  absorbed  by  the  large  quantity  of 
calcium  carbonate  present.  If  the  silicate  "s  fused  by  the  application  of  too  strong 
heat,  disintegration  of  the  mass  at  the  end  of  the  operation  with  water  cannot  be 
effected.  Moreover,  too  high  a  temperature  causes  volatilization  of  alkali  chlorids. 
The  mass  contracts  in  volume  during  the  ignition,  and  is  usually  easily  detached 
from  the  crucible.  Transfer  the  fused  mass  to  a  porcelain  dish,  thoroughly  slake 
with  hot  water,  and  grind  thoroughly  with  an  agate  pestle.  After  washing  5  times 
by  decantation  with  hot  water,  transfer  to  a  filter  and  wash  well,  300  cc.  of  wash 
water  being  sufficient.  To  the  filtrate  add  10  cc.  of  concentrated  hydrochloric 
acid,  and  evaporate  nearly  to  dryness  in  a  porcelain  dish.  Treat  with  hot  water 
and  2  cc.  of  hydrochloric  acid  and  filter  by  means  of  suction  through  a  small  filter 
into  a  150  cc.  Jena  beaker.  Concentrate  the  solution  to  30  cc,  add  1.5  cc.  of  platinic 
chlorid  solution  [I.  40  (b)  ],  evaporate  to  a  sirupy  consistency,  and  add  15  cc.  of 
2.25  N/1  acidulated  alcohol  (prepared  by  passing  hydrochloric  acid  gas  into  a  mix- 


II]  SOILS  27 

ture  of  2000  cc.  of  95%  alcohol  and  152  cc.  of  hydrochloric  acid,  sp.  gr.  1.20).  Fil- 
ter by  means  of  suction  through  a  small  filter,  wash  with  80%  alcohol,  then  with 
ammonium  chlorid  solution  [I,  40  (a)  ],  and  finally  with  80%  alcohol.  Dry  the 
precipitate  on  the  filter  and  wash  the  precipitate  with  hot  water  into  a  weighed 
platinum  dish,  using  suction.  Evaporate  to  dryness,  heat  in  a  drying  oven  for 
an  hour  at  120°C.,  cool  in  a  desiccator,  weigh  and  calculate  to  potassium  oxid  (KjO). 

TOTAL  ALKALIES. 

26  /.  Lawrence  Smith  Method.* — Official. 

(1)  Proceed  as  directed  under  25  to  the  point  indicated  by  the  phrase  "300  cc.  of 
wash  water  being  sufficient"  (the  point  at  which  the  ignited  mass  has  been 
disintegrated  and  thoroughly  washed  with  water).  The  filtrate  contains  the  sili- 
cate alkalies  in  the  form  of  chlorids  together  with  calcium  chlorid  and  hydroxid. 
Precipitate  the  calcium  at  once  with  ammonium  carbonate  solution;  allow  to  settle, 
decant  the  supernatant  liquid  into  a  porcelain  (or  platinum)  dish,  concentrate  and 
finally  transfer  the  precipitate  to  the  dish.  When  the  volume  is  reduced  to  about 
30  cc,  add  a  little  ammonium  carbonate  solution  and  ammonium  hydroxid,  heat 
and  filter  into  a  porcelain  (or  platinum)  dish,  evaporate  the  filtrate  to  dryness  on 
a  water  bath  and  expel  ammonium  salts  by  ignition.  Dissolve  the  residual  alkali 
chlorids  in  3-5  cc.  of  water;  a  little  black  or  dark  brown  flocculent  matter  usually 
remains  undissolved,  while  the  solution  may  also  contain  traces  of  calcium.  Add 
2-3  drops  of  ammonium  carbonate  and  ammonium  hydroxid,  warm  gently,  and  fil- 
ter through  a  very  small  filter  into  a  weighed  platinum  vessel.  Evaporate  to  dry- 
ness on  a  water  bath,  heat  the  alkali  chlorids  to  incipient  fusion,  cool,  and  weigh 
as  sodium  and  potassium  chlorids;  or, 

(2)  Determine,  by  the  above  method,  the  quantity  of  alkalies  in  the  insoluble 
residue,  12,  and  add  that  obtained  under  21  or  22. 

27  PHOSPHORUS  SOLUBLE  IN  N/5  NITRIC  ACID.— TENTATIVE. 

Digest  10  grams  of  air-dried  soil  in  a  stoppered  flask,  with  100  cc.  of  N/5  nitric 
acid,  for  exactly  5  hours  in  a  water  bath  kept  at  a  temperature  of  40°C.  Filter  the 
solution  through  a  dry  paper,  cool  to  room  temperature,  and  titrate  20  cc.  of  the 
filtrate  with  standard  potassium  hydroxid  solution  (carbonate-free),  using  phenol- 
phthalein  as  indicator.  From  the  data  thus  secured  calculate  the  number  of  cc. 
of  N/1  acid  and  of  water  to  make  exactly  1  or  2  liters  of  acid  of  N/5  strength  after 
allowing  for  the  quantity  neutralized  by  the  amount  of  soil  to  be  used  in  the  fol- 
lowing procedure: 

Place  200  grams  of  the  air-dried  soil  in  a  large,  dry,  glass-stoppered  bottle  and 
add  exactly  2000  cc.  of  N/5  nitric  acid  corrected  for  neutralization  as  above  de- 
scribed. With  soils  rich  in  available  phosphoric  acid,  100  grams  of  soil  and  1000  cc. 
of  acid  will  be  sufficient.  Digest  in  a  large  water  bath  at  a  temperature  of  40°C. 
for  exactly  5  hours,  shaking  thoroughly  each  half  hour.  At  the  end  of  the  digestion 
shake  the  contents  of  the  bottle  well  and  pour  quickly  upon  a  large,  dry,  ribbed  fil- 
ter of  2  thicknesses  of  paper  and  of  sufficient  size  to  receive  the  entire  contents  of 
the  bottle.  Collect  the  filtrate  in  a  dry  vessel,  pouring  back  on  the  filter  until  the 
filtrate  becomes  clear.  Evaporate  1000  or  500  cc.  of  the  filtrate,  according  to  the 
quantity  of  soil  used,  to  dryness  in  a  porcelain  dish;  add  a  few  cc.  of  nitric  acid  to 
oxidize  organic  matter,  etc.,  moisten  the  residue  with  hydrochloric  acid,  digest 
with  water,  and  filter  into  a  500  cc.  flask.  Add  a  solution  containing  15  grams  of 
ammonium  nitrate;  then  strong  ammonium  hydroxid  until  a  permanent  precipitate 
forms,   and  then  concentrated  nitric  acid  slowly  until  the  precipitate  dissolves. 


28  METHOD    OF    ANALYSIS 

Dilute  to  about  100  cc,  if  less  than  that  volume,  place  a  thermometer  in  the  flask, 
and  heat  to  S5°C.  Add  75  cc.  of  recently  prepared  molybdate  solution  [I,  4  (a)  ], 
digest  in  a  water  bath  at  80°C.  for  15  minutes,  with  occasional  shaking,  remove  from 
the  bath  and  allow  to  stand  at  least  10  minutes  before  filtering.  Continue  the  de- 
termination as  directed  under  I,  6  and  calculate  to  phosphorus  pentoxid  (PsOt). 

28  CALCIUM  CARBONATE  REQUIRED.— TENTATIVE. 

Place  100  grams  of  soil,  as  prepared  under  2,  in  a  400  cc.  wide-mouthed  bottle, 
add  250  cc.  of  N/1  potassium  nitrate,  stopper,  and  shake  continuously  for  3  hours 
in  a  shaking  machine,  or  every  5  minutes  by  hand.  Let  stand  overnight.  Draw 
off  125  cc.  of  the  clear,  supernatant  liquid,  boil  10  minutes  to  expel  carbon  dioxid, 
cool,  and  titrate  with  standard  sodium  hydroxid  solution,  1  cc.  of  which  is  equiva- 
lent to  4  mg.  of  calcium  carbonate  (0.001%  on  basis  of  the  weight  of  soil  used),  using 
phenolphthalein  as  indicator. 

29  STATEMENT  OF  RESULTS.-OFFICIAL. 

Calculate  all  results  of  soil  analysis  as  per  cent  of  the  soil  dried  to  constant  weight 
as  under  3  and  state  in  the  following  order: 

Insoluble  residue 

Soluble  silica — 

Manganomanganic  oxid  (Mn304) 

Potassium  oxid  (K2O) 

Sodium  oxid  (NajO) 

Calcium  oxid  (CaO) 

Magnesium  oxid  (MgO) 

Ferric  oxid  (Fe203) 

Aluminium  oxid  (AI2O3) , 

Phosphorus  pentoxid  (P2O6) 

Sulphur  trioxid  (SO3) 

Organic  carbon 

Inorganic  carbon 

Volatile  matter 

Total  nitrogen 

Total  phosphorus 

Total  potassium 

Phosphorus  soluble  in  N/5  acid 

Calcium  carbonate  required 

Total 

BIBLIOGRAPHY 

1  J.  Am.  Chem.  Soc,  1904,  26:  294,  1640. 

2  J.  Agr.  Rci.,3:  (II),  155. 

»  J.  Ind.  Eng.  Chem.,  1914,  6:  465. 

*  Fresenius.  Quantitative  Chemical  Analvsis.  Revised  and  amplified  transla- 
tion of  the  0th  German  ed.,  1906,  2:  1175;  Crookes.  Select  Methods  in  Chemical 
Analysis.  4th  ed.,  1005,  p.  23;  Wiley.  Principles  and  Practice  of  Agricultural 
Analysis.  1906,  1:  423;  U.S.  Geol.  Surv.  l?ull.  422,  p.  171;  Am.  J.  Sci.,  2nd  ser., 
1871,  50:  269;  Am.  Chem.,  1871,  1;  Ann.  Chem.  Pharm.,  1871,  159:  82. 


III.    PLANT   CONSTITUENTS. 

1  PREPARATION   OF  SAMPLE.— OFFICIAL. 

Thoroughly  cleanse  the  material  from  all  foreign  matter,  especially  from  adhering 
soil,  air-dry,  grind,  and  preserve  the  sample  in  tightly  stoppered  bottles. 

2  PREPARATION  OF  ASH.— OFFICIAL. 

Ignite  10-20  grams  of  the  substance,  in  a  fiat-bottomed  platinum  dish  in  a  muffle, 
at  a  comparatively  low  temperature.  Do  not  employ  a  full  red  heat  because  of  the 
danger  of  volatilizing  alkali  chlorids,  etc.  If  rich  in  silica  and  alkalies,  char  the 
material,  treat  with  water  to  dissolve  soluble  salts,  filter  through  an  ashless  filter, 
dry  the  filter  and  paper  and  incinerate,  add  the  filtrate  to  the  incinerated  residue, 
evaporate  to  dryness  and  ignite  at  a  low  red  heat.  If  rich  in  phosphates,  e.g.,  seeds 
and  animal  substances,  char  the  material,  dissolve  soluble  salts  in  dilute  acetic 
acid,  filter  through  an  ashless  filter,  wash  with  water,  dry  and  incinerate  the  filter 
and  residue,  add  the  filtrates  to  the  incinerated  residue,  evaporate  to  dryness,  and 
ignite  gently.  While  still  warm,  pulverize  the  whole  of  the  ash  as  obtained  above, 
mix  intimately  and  preserve  in  a  tightly  stoppered,  dry  bottle.  If  after  incineration 
the  ash  has  absorbed  moisture,  dry  thoroughly  at  low  redness  before  bottling. 

3  CARBON  DIOXID.-OFFICIAL. 

Determine  carbon  dio.xid  in  a  weighed  portion  of  the  ash  prepared  under  2.  Lib- 
erate the  carbon  dio.xid  by  treatment  with  dilute  hydrochloric  acid  in  any  of  the 
usual  forms  of  apparatus,  and  determine  the  increase  in  weight  of  the  potash 
bubs.  The  efficiency  of  the  apparatus  should  be  tested  by  blank  determinations 
conducted  upon  weighed  portions  of  pure  calcite. 

4  CARBON,  SAND  AND  SILICA.— OFFICIAL. 

Transfer  the  residue  from  the  carbon  dioxid  determination  to  a  beaker  or  evapo- 
rating dish;  evaporate  to  dryness;  pulverize  and  dry  thoroughly  to  render  the  silica 
insoluble.  Moisten  the  dry  residue  with  5-10  cc.  of  hj'drochloric  acid,  add  about 
50  cc.  of  water,  allow  to  stand  on  the  water  bath  for  a  few  minutes,  filter  through 
a  hardened  filter  and  wash  thoroughly.  Dilute  the  solution  and  washings  to  250 
cc.  or  other  convenient  volume.     Designate  as  .4. 

Wash  the  residue  from  the  filter  into  a  platinum  dish  and  boil  for  about  5  minutes 
with  approximately  20  cc.  of  a  saturated  solution  of  pure  sodium  carbonate,  add  a 
few  drops  of  pure  sodium  hydroxid  solution,  allow  the  solution  to  settle  and  decant 
through  a  tared  Gooch  filter.  Boil  the  residue  in  the  dish  with  sodium  carbonate 
solution  and  decant  as  before.  Repeat  the  process  again,  then  transfer  the  residue 
to  the  Gooch  filter,  wash  thoroughly,  first  with  hot  water,  then  with  a  little  dilute 
hydrochloric  acid,  and  finally  with  hot  water  until  free  from  cblorin.  Dry  the  filter 
and  contents  to  constant  weight  at  110°C.  to  determine  the  combined  weight  of 
carbonaceous  material  and  sand.  Incinerate;  the  loss  in  weight  represents  the 
carbonaceous  material;  the  residue  is  sand.  Confirm  by  microscopic  examination. 
Determine  the  soluble  silica  as  follows:  (1)  Combine  the  alkaline  filtrate  and  wash- 
ings, acidify  with  hydrochloric  acid,  evaporate  to  dryness  and  determine  the  silica 

29 


30  METHODS   OF   ANALYSIS  [Chap. 

in  the  usual  way;  or,  (2)  Treat  a  weighed  portion  of  the  ash,  as  prepared  under  2, 
with  dilute  hydrochloric  acid.  Evaporate  to  dryness;  pulverize  and  dry  thoroughly 
to  render  the  silica  insoluble.  Moisten  the  dry  residue  with  5-10  cc.  of  hydrochloric 
acid,  add  about  50  cc.  of  water,  allow  to  stand  on  the  water  bath  for  a  few  minutes, 
filter  on  an  ashless  filter,  wash,  dry,  ignite  and  weigh  to  determine  the  combined 
weight  of  the  silica  and  sand.  Deduct  the  weight  of  the  sand  found  above  to  obtain 
that  of  the  silica.  The  soluble  silica  cannot  be  separated  from  the  residue  after 
ignition. 

5  CARBON-FREE  ASH.-OFFICIAL. 

Subtract  the  weights  of  the  carbon  found  in  4  and  the  carbon  dioxid  found  in  3 
from  that  of  the  total  ash  used  in  3. 

6  FERRIC  AND  ALUMINIUM   OXIDS.— OFFICIAL. 

(Applicable  for  plant  materials  other  than  seeds.) 

Pipette  an  aliquot  of  A,  under  4,  corresponding  to  0.5  gram  of  ash,  into  a  250  cc. 
beaker.  If  ferrous  iron  is  present,  oxidize  it  by  boiling  with  a  few  cc.  of  hydrogen 
peroxid  or  of  concentrated  nitric  acid.  Cool,  add  ammonium  hydroxid  until  a 
precipitate  begins  to  form,  then  nitric  acid  until  just  clear,  and  finally  add  2-3  cc. 
of  concentrated  nitric  acid  in  excess.  Add  25  cc.  of  50%  ammonium  nitrate  solution, 
phosphate  free,  heat  to  40°C.,  and  add  slowly,  with  constant  shaking,  a  moderate 
excess  of  molybdate  solution  [1, 4  (a)],  and  allow  to  stand  for  1  or  2  hours  at  a  tem- 
perature not  exceeding  40°C.  After  standing  for  an  hour  pipette  5  cc.  of  the  clear 
solution  into  an  equal  volume  of  warm  molybdate  solution.  If  a  precipitate  forms 
in  the  test  portion  return  it  to  the  original  solution  and  add  more  molybdate  solu- 
tion. Allow  to  stand  at  room  temperature  for  several  hours,  preferably  overnight. 
Filter,  wash  with  about  75  cc.  of  ammonium  nitrate  solution  (2.5%,  phosphate  free, 
and  slightly  acidified  with  nitric  acid)  and  combine  the  filtrate  and  washings.  Des- 
ignate as  B.  Reserve  the  precipitate  for  the  determination  of  phosphoric  acid  as 
described  under  11.  i 

Without  concentrating  solution  5,  cai't-'ouply^eatralize  with  ammci,\  roxid, 

add  a  very  slight  excess  of  the  alkali,  avoiding  a  temperature  higher  than  40''C.,  and 
allow  to  stand  at  this  temperature  until  the  precipitate  completely  settles.  Filter 
the  clear  supernatant  liquid,  wash  the  precipitate  a  few  times  by  decantation  with 
hot  water  before  transferring  to  the  filter,  then  wash  4  or  5  times  on  the  filter.  Dis- 
solve the  precipitate  on  the  filter  with  hot  nitric  acid  (1  to  5),  wash  and  reprecipitate 
as  before.  The  combined  filtrates  and  washings  from  the  first  and  second  precipi- 
tations should  not  exceed  500  cc.  and  should  not  be  concentrated  by  evaporation. 
Designate  as  C  and  reserve  for  the  determination  of  calcium  and  magnesium  as 
described  under  8.  The  same  filter  may  be  used  for  the  second  filtration,  and  the 
volume  of  the  solution  for  the  reprecipitation  need  not  exceed  100  cc.  Before  the 
second  filtration  is  made,  a  small  quantity  of  ashless  filter  paper  pulp  should  be 
added  in  order  to  facilitate  the  washing  and  leave  the  precipitate  finely  divided 
after  the  ignition,  so  that  it  can  be  easily  fused  with  potassium  hydrogen  sulphate  for 
the  iron  determination.  Dry  and  ignite  the  precipitate  and  weigh  as  ferric  and 
aluminium  oxids. 

The  iron  oxid  is  determined  in  the  following  manner :  Fuse,  in  a  platinum  crucible, 
the  ignited  precipitate  with  about  4  grams  of  fused  potassium  hydrogen  sulphate. 
This  fusion  takes  but  a  few  minutes  and  must  not  be  continued  beyond  the  time 
actua  ly  needed.  When  completed  the  crucible  is  set  aside  and  allowed  to  cool. 
Add  5  cc.  of  concentrated  sulphuric  acid  and  heat  until  copious  fumes  of  sulphuric 


in]  PLANT    CONSTITUENTS  31 

acid  are  given  off.  Cool,  transfer  to  a  flask,  add  water,  and  digest  till  the  solution  is 
clear.  Reduce  with  zinc,  cool,  titrate  with  N/50  potassium  permanganate  and  cal- 
culate to  ferric  oxid. 

If  it  is  desired  to  use  a  larger  amount  of  the  sample  for  the  iron  determination, 
evaporate  a  suitable  aliquot  of  A,  under  4,  with  sulphuric  acid,  reduce  with  zinc, 
and  titrate  as  above. 

MANGANESE,  CALCIUM  AND  MAGNESIUM. 

(Applicable  for  plant  materials  other  than  seeds.) 

7  Method  I. —Official. 

To  an  aliquot  of  A,  under  4,  corresponding  to  0.5-2  grams  of  ash,  add  a  quantity 
of  pure  ferric  chlorid  solution,  more  than  sufficient  to  combine  with  the  phosphoric 
acid  which  may  be  present,  and  neutralize  with  ammonium  hydroxid.  Dissolve  the 
precipitate  in  a  very  slight  excess  of  hydrochloric  acid  and  add  1-2  grams  of  sodium 
acetate.  Boil  for  1-2  minutes,  filter  at  once,  and  wash  with  boiling  water.  Dissolve 
the  precipitate  in  hydrochloric  acid  and  reprecipitate  as  above.  Concentrate  the 
combined  filtrates  and  washings  to  about  50  cc.  and  determine  manganese,  calcium 
and  magnesium  as  directed  under  II,  14,  15,  and  16. 

8  Method  11.— Tentative. 

Calcium. — Make  alkaline  with  ammonium  hydroxid  the  combined  filtrates  and 
washings,  C,  under  6,  and  proceed  as  directed  under  11,15.  If  the  ignited  calcium 
oxid  has  a  brown  coloration,  due  to  manganese,  dissolve  in  dilute  hydrochloric  acid 
and  determine  the  manganese  as  directed  below.  Deduct  the  weight  of  mangano- 
manganic  oxid  thus  obtained  from  the  weight  of  the  impure  calcium  oxid. 

Manganese. — Acidify  the  combined  filtrates  and  washings  from  the  calcium  de- 
termination and  evaporate  to  dryness  in  a  porcelain  casserole.  Expel  the  ammonium 
salts  by  carefully  heating  the  casserole  from  above,  treat  with  a  few  cc.  of  hydro- 
chloric acid  and  water,  filter  off  molybdic  acid,  and  wash  the  precipitate  until  it  is 
free  frc  orin.     Bring  the  filtrate  to  a  volume  of  100  cc,  add  1-2  drops  of  bromin, 

make  a  with  a'^^monium  h/drSx'"^'";  ..1'  let  stand  for  several  minutes  without 

agitation.  Filter  off  the  precipitated  manganese,  wash,  dry,  ignite,  and  weigh  the 
precipitate  as  manganomanganic  oxid.  To  this  add  the  weight  of  the  mangano- 
manganic  oxid  found  as  an  impurity  in  the  calcium  determination. 

Magnesium. — Concentrate  the  alkaline  filtrate  from  the  manganese  determination 
to  75  cc.  and  determine  magnesium  as  directed  under  II,  16. 

PHOSPHORIC  ACID. 

9  Method  I.— Official. 

Determine  phosphoric  acid  in  an  aliquot  of  A,  under  4,  corresponding  to  0.2-1 
gram  of  ash,  as  directed  under  I,  6  or  9. 

10  Method  II. —Official. 

Determine  phosphoric  acid  in  the  plant  substance  as  directed  under  1, 6,  using  suf- 
ficient material  to  give  0.2-1  gram  of  ash  in  the  aliquot  of  the  solution  employed. 

11  Method  III. -Official. 

The  phosphomolybdate  precipitate  obtained  in  6  is  used  for  the  determination 
of  phosphoric  acid  as  directed  under  I,  6,  beginning  with  "Dissolve  the  precipitate 


32  METHODS   OF   ANALYSIS  [Chap. 

on  the  filter  with  ammonium  hydroxid,  etc."  or  as  under  I,  9  (a),  beginning  with 
"Wash  with  cold  water  until  the  filtrate  from  2  fillings  of  the  filter  yields  a  pink 
color,  etc." 

12  SULPHURIC  ACID,  SODIUM,  AND  POTASSIUM.— OFFICIAL. 

Boil  an  aliquot  of  A,  under  4,  corresponding  to  0.5-1  gram  of  ash,  add  barium 
chlorid  solution  in  small  quantities  until  no  further  precipitate  is  formed,  and  pro- 
ceed as  directed  under  II,  20  and  21 . 

■|3  CHLORIN.— OFFICIAL. 

Determine  as  silver  chlorid,  either  gravimetrically  or  by  one  of  the  standard 
volumetric  procedures  (as  the  Volhard  method  given  below),  in  a  nitric  acid  or 
aqueous  solution  of  the  ash. 

Volhard  Methods 

14  REAGENTS. 

(a)  N/10  silver  nitrate. 

(b)  N/iO  ammonium,  or  potassium  sulphocyanate. 

(C)  Ferric  indicator. — Saturated  solution  of  ferric  alum. 

(d)  Nitric  acid. — Free  from  lower  oxids  of  nitrogen,  secured  by  diluting  the 
usual  pure  acid  with  about  1/4  part  of  water,  and  boiling  till  perfectly  colorless. 

15  DETERMINATION. 

Dissolve  a  weighed  portion  of  the  ash,  prepared  under  2,  in  nitric  acid  (1  to  10). 
filter  and  wash  with  water.  Add  a  known  volume  of  the  N/10  silver  nitrate  in  slight 
excess  to  the  combined  filtrate  and  washings.  Stir  well,  filter,  and  wash  the  silver 
chlorid  precipitate  thoroughly.  To  the  filtrate  and  washings  add  5  cc.  of  the  ferric 
indicator  and  a  few  cc.  of  the  nitric  acid.  Titrate  the  excess  of  silver  with  the 
N/10  sulphocyanate  until  a  permanent  light  brown  color  appears.  Calculate  the 
amount  of  chlorin. 

16  POTASSIUM  IN  PLANTS.-OFFICIAL. 

Determine  potassium  as  directed  under  I,  42,  using  sufficient  plant  material  to 
yield  0.5-1  gram  of  ash  in  the  aliquot  of  the  solution  used  for  the  potassium  determi- 
nation. 

SULPHUR  IN  PLANTS. 

17  Peroxid  Method. — Official. 

Place  1.5-2.5  grams  of  material  in  a  nickel  crucible  of  about  100  cc.  capacity  and 
add  5  grams  of  pure  anhydrous  sodium  carbonate.  Mix  thoroughly,  using  a  nickel  or 
platinum  rod,  and  moisten  with  approximately  2  cc.  of  water.  Add  pure  sodium 
peroxid,  approximately  0.5  gram  at  a  time,  thoroughly  mixing  the  charge  after  each 
addition.  Continue  adding  the  peroxid  until  the  mixture  becomes  nearly  dry  and 
quite  granular,  requiring  usually  about  5  grams  of  peroxid.  Place  the  crucible  over 
a  low  alcohol  or  other  sulphur-free  flame  and  heat  carefully  with  occasional  stirring 
until  the  contents  are  fused.  (Should  the  material  ignite,  the  determination  is 
worthless.)  After  fusion  remove  the  crucible,  allow  to  cool  somewhat,  and  cover  the 
hardened  mass  with  peroxid  to  a  depth  of  about  0.5  cm.  Heat  gradually,  and  finally 
with  full  flame  until  fusion  again  takes  place,  rotating  the  crucible  from  time  to 
time  in  order  to  bring  any  particles  adhpring  to  the  sides  into  contact  with  the 
oxidizing  material.     Continue  the  heating  for  10  minutes  after  fusion  is  complete. 


ni]  PLANT    CONSTITUENTS  33 

Cool  somewhat,  place  the  warm  crucible  and  contents  in  a  600  cc.  beaker  and  care- 
fully add  about  100  cc.  of  water.  After  the  initial  violent  action  has  ceased,  wash 
the  material  out  of  the  crucible,  make  slightly  acid  with  hydrochloric  acid  (adding 
small  portions  at  a  time),  transfer  to  a  500  cc.  flask,  cool,  and  make  to  volume. 
Filter,  and  determine  sulphates  in  200  cc.  of  the  filtrate  as  directed  under  II,  20. 

18  CHLORIN  IN  PLANTS.— TENTATIVE. 

Moisten  5  grams  of  the  substance  in  a  platinum  dish  with  20  cc.  of  a  5%  solution  of 
sodium  carbonate,  evaporate  to  dryness,  and  ignite  as  thoroughly  as  possible  at  a 
temperature  not  exceeding  dull  redness.  Extract  with  hot  water,  filter  and  wash. 
Return  the  residue  to  the  platinum  dish  and  ignite  to  an  ash;  dissolve  in  nitric  acid, 
add  this  solution  to  the  water  extract  and  determine  chlorin  as  directed  under  15. 

BIBLIOGRAPHY. 

'  Sutton.    Volumetric  Analysis.     10th  ed.,  1911,  p.  145. 


IV.    WATERS. 

POTABLE  WATER. 

TURBIDITY.— TENTATIVE. 

1  REAGENTS. 

(a)  Standard  turbidity  solution. — Weigh  out  1  gram  of  elutriated  fuller's  earth 
previously  dried  and  sifted  through  a  200  mesh  sieve.  Make  up  to  a  liter.  If  the 
fuller's  earth  is  of  good  quality  and  the  proper  degree  of  fineness,  this  stock  solution 
has  a  turbidity  of  1000.     Check  the  stock  solution  with  a  Jackson  turbidimeter. 

(b)  Turbidity  standards. — Prepared  by  dilution  of  (a). 

2  DETERMINATION. 

Determine  the  turbidity  of  the  sample  with  a  Jackson  turbidimeter  equipped 
with  either  candle  or  electric  light.  If  the  turbidity  is  less  than  100,  which  pro- 
hibits the  use  of  the  turbidimeter,  determine  by  direct  comparison  with  turbidity 
standards  contained  in  bottles  of  clear  white  glass. 

COLOR.— TENTATIVE. 

3  REAGENTS. 

(a)  Standard  color  solu'ion. — Dissolve  1.246  grams  of  potassium  platinic  chlorid 
(PtCl42KCl)  and  1  gram  of  crystallized  cobalt  chlorid  (C0CI26H2O)  in  a  small  quan- 
tity of  water,  add  100  cc.  of  concentrated  hydrochloric  acid  and  make  up  to  1  liter 
with  water.     This  stock  solution  has  a  color  of  500. 

(b)  Color  standards. — Prepared  by  dilution  of  (a). 

4  DETERMINATION. 

Compare  the  color  of  the  sample,  freed  from  suspended  matter,  with  color 
standards  in  tubes  of  clear  white  glass. 

5  ODOR.— TENTATIVE. 

Shake  the  vessel  containing  the  sample  and  note  the  odor.  Heat  a  portion  of  the 
sample  just  to  boiling  and  note  the  odor. 

6  TOTAL  SOLIDS.-OFFICLAL. 

Thoroughly  shake  the  vessel  containing  the  sample  and  pipette  100  cc.  of  the  un- 
filtered  water  into  a  weighed  platinum  dish.  If  the  sample  contains  much  suspended 
matter,  shake,  pour  rapidly  into  a  100  cc.  measuring  cylinder,  and  transfer  without 
delay  to  a  weighed  platinum  dish;  evaporate  to  dryness  and  heat  to  constant  weight 
at  105°C.  In  the  case  of  highly  mineralized  waters  it  is  advisable  to  weigh  again 
after  drying  at  1S0°C. 

7  SOLIDS  IN  SOLUTION.— OFFICIAL. 

Allow  the  sample  to  stand  until  all  sediment  has  settled,  and  filter  if  necessary 
to  secure  a  perfectly  clear  liquid.  Occasiona  ly  a  clear  filtrate  can  only  be  obtained 
by  the  use  of  alumina  cream  but  this  should  be  avoided  if  possible.     Evaporate  100- 

35 


36  METHODS    OF   ANALYSIS  [Chap. 

250  cc.  to  dryness  in  a  weighed  platinum  dish.     Heat  to  constant  weight  at  105**C. 
In  the  case  of  highly  mineralized  waters  it  is  advisable  to  weigh  again  after  drying 
at  180°C. 
g  SUSPENDED  MATTER.— OFFICIAL. 

(1)  The  difference  between  the  values  for  total  solids  and  dissolved  solids  rep- 
resents the  suspended  matter;  or,  (2)  Determine  the  suspended  matter  directly  by 
filtering  a  suitable  quantity  of  the  water  through  a  tared  Gooch  crucible,  suitably 
prepared,  and  weighing  after  drying  at  105°C. 

9  IGNITED  RESIDUE.— OFFICIAL. 

Ignite  the  residue  from  6  at  a  low  red  heat  until  the  ash  is  white  or  nearly  so. 
Note  any  odor  or  change  in  color  produced  during  ignition.  Record  the  weight 
of  the  ignited  residue  and  calculate  the  loss  on  ignition. 

FREE  AND  ALBUMINOID  AMMONIA.— OFFICIAL. 

10  REAGENTS. 

(a)  Saturated  solution  of  sodium  carbonate. 

(b)  Ammonia-free  water. 

(C)  Standard  ammoriium  chlorid  solution. — One  cc.  is  equivalent  to  0.01  mg.  of 
nitrogen  in  the  form  of  ammonia  (NH3). 

(d)  Nessler  reagent. — Dissolve  50  grams  of  potassium  iodid  in  aminimum  quantity 
of  cold  water.  Add  a  saturated  solution  of  mercuric  chlorid  until  a  slight  perma- 
nent precipitate  is  formed.  Add  400  cc.  of  50%  solution  of  potassium  hydroxid  (or 
an  equivalent  quantity  of  sodium  hydroxid),  dilute  to  1  liter,  allow  to  settle,  and 
decant. 

(e)  Alkaline  potassium  permanganate  solution. — Dissolve  200  grams  of  potassium 
hydroxid  and  8  grams  of  potassium  permanganate  in  water  and  dilute  to  1  liter. 


11 


DETERMINATION. 


Connect  a  flask  of  about  1500  cc.  capacity  with  an  upright  bulb  condenser  by 
means  of  a  rather  large  glass  tube  and  a  soft  rubber  stopper  or  a  recently  extracted 
cork  stopper.  Place  in  the  flask  5  cc.  of  the  saturated  solution  of  sodium  carbonate 
and  500  cc.  of  ammonia-free  water.  Distil  into  50  cc.  Nessler  tubes  until  no  further 
traces  of  ammonia  are  indicated  on  the  addition  of  2  cc.  of  the  Nessler  reagent  to 
50  cc.  of  the  distillate.  Continue  the  distillation  until  the  volume  of  the  solution 
in  the  flask  has  been  reduced  to  about  200  cc.  Cool  slightly,  add  500  cc.  of  the  water 
under  examination,  and  distil,  at  the  rate  of  1  tubeful  in  15  minutes,  into  50  cc. 
Nessler  tubes  until  ammonia  ceases  to  be  given  off'  (4  or  5  tubes  are  usually  sufficient). 
Add  2  cc.  of  the  Nessler  reagent  to  each  tube  and  let  stand  10  minutes.  Freshly 
prepare  in  a  similar  manner  other  tubes  containing  known  amounts  of  the  standard 
ammonium  chlorid,  made  up  to  50  cc.  with  ammonia-free  water,  and  compare  the 
nesslerized  distillates  with  these.  Report  as  milligrams  per  liter  of  nitrogen  in  the 
form  of  free  ammonia  (NHj).  Cool  the  flask  and  add  50  cc.  of  the  alkaline  perman- 
ganate recently  boiled.  Distil,  at  the  rate  of  1  tubeful  in  15  minutes,  into  50  cc. 
Nessler  tubes  until  ammonia  ceases  to  come  off.  Nesslerize  and  compare  as  in  the 
determination  of  free  ammonia.  Report  as  milligrams  per  liter  of  nitrogen  in  the 
form  of  albuminoid  ammonia  (NHj). 


rV]  WATERS  37 

NITROGEN   IN   THE    FORM    OF    NITRITE.— OFFICIAL. 

12  REAGENTS. 

(a)  Concentrated  hydrochloric  acid. — Sp.  gr.  1.2. 

(b)  Sulphanilic  acid  solution. — Dissolve  1  gram  of  sulphanilic  acid  in  100  cc.  of 
hot  water. 

(C)  Alpha-naphthylamin  hydrochlorid  solution. — Boil  0.5  gram  of  the  salt  with 
100  cc.  of  water  for  10  minutes  at  constant  volume. 

(d)  Standard  nitrite  solution. — Dissolve  1.1  gram  of  silver  nitrite  in  nitrite-free 
water,  precipitate  the  silver  with  sodium  chlorid  solution  and  dilute  to  1  liter,  mix 
and  allow  to  settle.  Dilute  100  cc.  to  1  liter  and  then  10  cc.  of  this  solution  to  1 
liter,  using  in  each  case  nitrite-free  water.  Each  cc.  of  the  last  solution  is  equivalent 
to  0.0001  mg.  of  nitrogen  as  nitrite. 

1 3  DETERMINATION. 

Place  100  cc.  of  the  water  in  a  100  cc.  Nessler  tube  and  treat  with  1  or  2  drops  of 
concentrated  hydrochloric  acid.  Add  1  cc.  of  the  sulphanilic  acid,  1  cc.  of  the  alpha- 
naphthylamin  hydrochlorid,  and  thoroughly  mix.  Set  aside  for  30  minuteswith  other 
Nessler  tubes  containing  known  amounts  of  the  standard  nitrite  made  up  to  100  cc. 
with  nitrite-free  water,  and  treated  with  hydrochloric  acid,  sulphanilic  acid,  and 
alpha-naphthylamin  hydrochlorid  in  the  manner  just  described.  Determine  the 
amount  of  nitrite  by  comparing  the  depth  of  pink  color  in  the  known  and  unknown 
solutions.     Record  as  nitrogen  in  the  form  of  nitrite. 

NITROGEN  IN  THE  FORM   OF   NITRATE. 

Phenoldisulphonic  Acid  Method. — Official. 
(For  water  of  low  chlorin  content.) 

14  REAGENTS. 

(a)  Phenoldisulphonic  acid  solution. — Dissolve  25  grams  of  pure  white  phenol  in 
150  cc.  of  concentrated  sulphuric  acid,  add  75  cc.  of  fuming  sulphuric  acid  (13-15% 
SOs)  and  heat  at  100°C.  for  2  hours. 

(b)  Standard  nitrate  solution. — Dissolve  0.722  gram  of  pure  potassium  nitrate  in 
1  liter  of  nitrate-free  water.  Evaporate  50  cc.  of  this  solution  to  dryness  in  a  porce- 
lain dish;  treatwith2cc.of  the  phenoldisulphonic  acid  solution,  rubbing  with  a  glass 
rod  to  insure  intimate  contact.  Dilute  to  500  cc. ;  1  cc.  is  equivalent  to  0.01  mg.  of  ni- 
trogen as  nitrate.  This  solution  is  permanent.  Standards  for  comparison  are  pre- 
pared by  adding  ammonium  hydroxid  to  measured  volumes  of  it  in  100  cc.  Nessler 
tubes. 

(C)  Standard  silver  sulphate  solution. — Dissolve  4.3969  grams  of  silver  sulphate, 
free  from  nitrate,  in  1  liter  of  water;  1  cc.  is  equivalent  to  1  mg.  of  chlorin. 
(d)  Ammonium  hydroxid. — Sp.  gr.  0.90. 

15  DETERMINATION. 

Take  100  cc.  of  the  sample,  or  an  amount  that  will  contain  0.05  mg.  or  less  of 
nitrogen  as  nitrate,  and  add  standard  silver  sulphate,  precipitating  all  but  about 
0.5  mg.  of  the  chlorin.  Heat  to  boiling,  allow  to  settle,  or  add  a  little  alumina  cream, 
filter,  and  wash  with  small  amounts  of  hot  water.  Evaporate  the  filtrate  to  drynes* 
in  a  porcelain  dish  on  the  water  bath;  when  cool,  treat  with  2  cc.  of  the  pheuoldieul- 
phonic  acid  solution  as  in  14  (b).     Dilute  with  water  and  add  slowly  ammonium  hy- 


38  METHODS   OF  ANALYSIS  [Chap. 

droxitl  until  the  maximum  color  is  developed.  Transfer  to  a  colorimetric  cylinder, 
filter  if  necessary,  and  compare  with  the  standards  in  the  usual  manner.  Record  as 
nitrogen  in  the  form  of  nitrate. 

Reduction  Method. — Official. 
(For  water  of  high  chlorin  content.) 

16  REAGENTS. 

(a)  Sodium  or  potassium  hydroxid  solution. — Dissolve  250  grams  of  the  purest 
hydroxid  obtainable  in  1250  cc.  of  water  and  boil  down  to  1  liter. 

(b)  Aluminium  foil. — Use  strips  about  10  cm.  long,  weighing  about  0.5  gram. 

17  DETERMINATION. 

Place  10  cc.  of  the  sample  in  a  100  cc.  test  tube  and  dilute  to  exactly  50  cc. ;  add  5  cc. 
of  the  sodium  hydroxid  and  a  strip  of  the  aluminium  foil.  Close  the  mouth  of  the 
test  tube  with  a  rubber  stopper  carrying  a  U-shaped  glass  tube  connected  with  a 
second  test  tube  containing  about  50  cc.  of  ammonia-free  water  acidified  with  hydro- 
chloric acid,  which  serves  as  a  trap  to  catch  any  ammonia  which  might  escape.  Allow 
to  stand  at  room  temperature  for  12  hours  or  more  until  reduction  is  complete.  Trans- 
fer the  contents  of  the  first  tube  to  a  Kjeldahl  flask  and  distil.  Cool  the  distillates 
and  nesslerize  as  directed  under  1 1  ;  also  nesslerize  the  solution  in  the  trap.  Record 
as  nitrogen  in  the  form  of  nitrate. 

CHLORIN.— OFFICIAL. 

18  REAGENTS. 

(a)  N/20  sulphuric  acid. 

(b)  N /20  sodium,  carbonate. 

(C)  Potassium  chromate  indicator. — Dissolve  5  grams  of  potassium  chromate  in 
water,  add  a  solution  of  silver  nitrate  until  a  slight  permanent  red  precipitate  is 
produced,  filter,  and  dilute  to  100  cc. 

(d )  Standard  silver  nitrate  solution. — Dissolve  4.791  grams  of  silver  nitrate  in  water 
and  dilute  to  1  liter;  1  cc.  is  equivalent  to  1  mg.  of  chlorin.  Check  by  titration  against 
a  standardized  solution  of  sodium  chlorid. 


19 


DETERMINATION. 


To  100  CC.  of  the  water  add  a  few  drops  of  phenolphthalein.  If  a  red  color  appears, 
titrate  the  carbonates  thus  indicated  to  bicarbonates  with  N/10  or  N/20  sulphuric 
acid.  If  the  water  is  acid  to  methyl  orange,  add  N/20  sodium  carbonate  to  neutralize 
the  acidity.  Add  1  cc.of  the  potassium  chromate  and  titrate  with  the  standard  silver 
nitrate.  Correct  for  the  amount  of  silver  nitrate  necessary  to  give  in  100  cc.  of  chlorin- 
free  water  with  1  cc.  of  the  chromate,  the  shade  obtained  at  the  end  of  the  titration 
of  the  sample.  lodids  and  bromids  are  not  usually  found  in  interfering  quantities 
in  potable  water.     However,  if  they  are  present  make  the  equivalent  correction. 

If  chlorids  are  present  in  very  small  quantities  concentrate  500  or  1000  cc.  in  a  por- 
celain dish  to  100  cc,  rub  down  the  sides  of  the  dish  carefully,  add  1  cc.  of  the  indicator 
and  titrate  as  described  above.  If  sufficient  chlorids  are  present  in  100  cc.  of  the  water 
to  consume  more  than  25  cc.  of  the  standard  silver  nitrate,  determine  by  precipita- 
tion in  nitric  acid  solution  and  weigh  the  silver  chlorid. 


IV]  WATERS  39 

OXYGEN  REQXTIRED. 

Method  I.— Official. 

20  REAGENTS. 

(a)  Standard  potassium  permanganate  solution. — Dissolve  0.3952  gram  of  potas- 
sium permanganate  in  1  liter  of  water;  each  cc.  has  0.1  mg.  of  oxygen  available  for 
oxidation. 

(b)  Standard  oxalic  acid  solution. — Dissolve  0.7875  gram  of  crystallized  oxalic  acid 
in  1  liter  of  water. 

Determine  the  value  of  the  oxalic  acid  in  terms  of  the  permanganate  by  boiling 
10  cc.  of  the  oxalic  acid  and  200  cc.  of  redistilled  water  (prepared  by  treating  distilled 
water  with  alkaline  permanganate  and  distilling)  with  10  cc.  of  sulphuric  acid  (1 
to  3)  and  titrating,  while  still  boiling,  with  the  standard  permanganate  to  the  appear- 
ance of  a  pink  color. 

21  DETERMINATION. 

Add  10  cc.  of  sulphuric  acid  (1  to  3)  to  200  cc.  of  the  water  in  a  porcelain  dish  and 
heat  to  boiling.  Add  from  a  burette  the  standard  permanganate  until  the  water 
is  distinctly  red  and  boil  for  10  minutes,  adding  more  of  the  standard  permanganate 
from  time  to  time  to  maintain  the  red  color.  Add  10  cc.  of  the  standard  oxalic  acid 
and  titrate  back  with  the  standard  permanganate  to  a  pink  color.  From  the  total 
number  of  cc.  used  of  the  permanganate  subtract  the  number  of  cc.  equivalent  to  10  cc. 
of  the  oxalic  acid.  The  result  gives  the  number  of  cc.  of  the  permanganate  required 
for  200  cc.  of  the  water.  Correct  for  sulphids,  nitrites  and  ferrous  salts,  if  present,  by 
subtracting  the  number  of  cc.  of  the  standard  permanganate  absorbed  by  another 
200  cc.  portion  of  the  sample  when  treated  as  above,  digesting  at  room  temperature 
for  3  minutes. 

Method  II.     {Schulze-Trommsdorf  Method.^) — Tentative. 
(To  be  used  when  the  chlorin  content  of  the  sample  is  high.) 

22  REAGENTS. 

(a)  50%  sodium  hydroxid  solution. 

Other  reagents  and  standard  solutions  are  described  under  20. 

23  DETERMINATION. 

Introduce  100  cc.  of  the  water  to  be  examined  in  a  300  cc.  flask,  add  0.5  cc.  of  the 
sodium  hydroxid  and  10  cc.  of  the  permanganate,  boil  for  10  minutes,  allow  to  cool  to 
50°-60°C.  and  add  5  cc.  of  the  dilute  sulphuric  acid  and  10  cc.  of  the  standard  oxalic 
acid.  As  soon  as  the  liquid  has  become  perfectly  colorless,  and  while  constantly  agita- 
ting, cautiously  add  from  a  burette,  drop  by  drop,  the  standard  permanganate,  until 
the  liquid  acquires  a  faint  permanent  redness.  The  permanganate  required  to 
effect  this  is  the  quantity  required  for  the  decomposition  of  the  organic  matter  in 
the  100  cc.  of  water. 

If  100  cc.  of  the  water  require  more  than  4  cc.  of  the  permanganate  for  the  oxidation 
of  organic  matter,  a  second  determination  must  be  made  using  more  of  the  per- 
manganate and  a  correspondingly  larger  quantity  of  the  sodium  hydroxid,  as  unde- 
composed  permanganate  remaining  after  boiling  must  be  at  least  twice  as  great  as 
the  quantity  decomposed. 


40  METHODS   OF   ANALYSIS  [Chap. 

DISSOLVED  OXYGEN. 

Method  I.     (Winkler  Method  as  Modified  by  Drown  and  Hazen.^)~Tentativ.. 
(When  less  than  0.1  mg.  of  nitrite  nitrogen  per  liter  is  present.) 

24  REAGENTS. 

(a)  Manganous  sulphate  solution. — Dissolve  48  grams  of  nianganous  sulphate  in 
100  cc.  of  water. 

(b)  Sodium  hydroxid-potassium  iodid  solution. — Dissolve  360  grams  of  sodium 
hydroxid  and  100  grams  of  potassium  iodid  in  1  liter  of  water. 

(C)  Sulphuric  acid. —  (Sp.  gr.  1.4).  Mi.x  equal  weights  of  concentrated  sulphuric 
acid  and  water. 

(d)  Standard  sodium  thiosulphate  solution. — Dissolve  6.2  grams  of  recrystallized 
sodium  thiosulphate  in  1  liter  of  water.  This  gives  a  N/40  solution,  each  cc.  of  which 
is  equivalent  to  0.2  mg.  of  oxygen  or  0.1395  cc.  of  oxygen  at  O'^C.  and  760  mm.  pressure. 
This  solution  should  be  standardized  occasionally  against  N/40  potassium  dichromate. 

(e)  Starch  indicator. — Mix  about  2  grams  of  clean  starch  with  cold  water  to  a  thin 
paste;  pour  into  about  200  cc.  of  boiling  water.  Boil  for  a  few  minutes.  This  solu- 
tion should  be  freshly  prepared. 

25  COLLECTION  OF  SAMPLE. 

Collect  the  sample  in  a  carefully  calibrated  glass  stoppered  bottle,  approximately 
250  cc.  capacity,  by  means  of  an  apparatus  designed  to  avoid  the  entrainment  or 
absorption  of  any  oxygen  from  the  atmosphere.     Note  the  temperature. 

26  DETERMINATION. 

Add  approximately  2  cc.  of  the  manganous  sulphate  and  2  cc.  of  the  sodium  hydrox- 
id-potassium iodid,  delivering  both  of  these  solutions  beneath  the  surface  of  the 
liquid  by  means  of  a  pipette.  Insert  the  stopper  and  mix  the  contejits  of  the  bottle 
by  shaking.  Allow  the  precipitate  to  settle.  Remove  the  stopper;  add  about  2  cc. 
of  sulphuric  acid  and  mix  thoroughly.  Rinse  the  contents  of  the  bottle  into  a  flask; 
titrate  with  N/40  sodium  thiosulphate,  using  a  few  cc.  of  the  starch  indicator  toward 
the  end  of  the  titration.  Do  not  add  the  starch  until  the  color  has  become  a  faint 
yellow;  titrate  until  the  blue  color  disappears.  Express  the  results  in  milligrams 
per  liter  and  in  percentage  of  saturation.^  This  latter  determination  is  the  ratio  of 
the  amount  of  gas  present  to  the  maximum  amount  capable  of  being  dissolved  by 
distilled  water  at  the  same  temperature  and  pressure. 

Method  II.     (Winkler  Method  as  Modified  by  Rideal  and  Stewart.*) — Tentative. 
(When  more  than  0.1  mg.  of  nitrite  nitrogen  per  liter  is  present.) 

27  .    REAGENTS. 

(a)  N/10  potassium  permanganate. 

(b)  S%  potassium  oxalate  solution. 
Other  reagents  are  described  under  24. 

28  COLLECTION   OF    SAMPLE. 

Proceed  as  directed  under  25. 


IV]  WATERS  41 

29  DETEHMINATION. 

Preli7ninary  test. — Determine  the  amount  of  the  permanganate  required  to  oxi- 
dize the  nitrite  to  nitrate  by  acidifying  a  preliminary  sample  of  50  cc.  with  1  cc.  of 
the  sulphuric  acid  and  adding  the  permanganate  until  a  slight  pink  color  remains 
after  standing  10  minutes.  Calculate  the  amount  of  the  permanganate  required  for 
a  sample  collected  as  described  under  25. 

To  the  sample  add  1  cc.  of  the  sulphuric  acid  and  about  0.1  cc.  of  the  perman- 
ganate in  excess  of  the  calculated  amount  required  to  oxidize  the  nitrite  to  nitrate. 
If  more  than  10  cc.  of  the  permanganate  are  required  add  an  additional  1  cc.  of  the 
sulphuric  acid.  Rotate  the  bottle  and  allow  to  stand  for  10  minutes,  after  which 
destroy  any  excess  of  the  permanganate  by  adding  from  a  pipette  0.5-1  cc.  of  the 
oxalate.  Insert  the  stopper  and  rotate  as  before.  The  color  quickly  disappears, 
and  when  decolorized  add  approximately  2  cc.  of  the  manganous  sulphate  and  2  cc. 
of  the  sodium  hydroxid-potassium  iodid  and  proceed  as  in  26.  Express  the  results 
in  milligrams  per  liter  and  percentage  saturation.' 

MINERAL  WATER. 

30  SPECIFIC   GRAVITY.-TENTATIVE. 
Determine  specific  gravity  at  -^qt  by  means  of  a  pycnometer. 

31  SOLIDS   IN   SOLUTION.— OFFICIAL. 

Determine  as  directed  under  7. 

32  IGNITED   RESIDUE.— OFFICIAL. 

Determine  as  directed  under  9. 

33  FREE  AND  ALBUMINOID  AMMONIA.— OFFICIAL. 
Determine  as  directed  under  1 1 . 

34  NITROGEN  IN   THE   FORM   OF   NITRITE. -OFFICIAL. 
Determine  as  directed  under  13. 

35  NITROGEN  IN  THE  FORM  OF  NITRATE.— OFFICIAL. 
Determine  as  directed  under  15  or  17. 

36  CHLORIN.-OFFICIAL. 
Determine  as  directed  under  19. 

37  HYDROGEN  SULPHID.— TENTATIVE. 

Place  0.5-2  cc.  of  N/100  iodin  in  a  500  cc.  flask  and  add  the  water  until  the  color 
of  the  iodin  disappears.  Add  5  cc.  of  the  starch  indicator  and  then  N/100  iodin  until 
a  blue  color  appears.  Fill  the  flask  to  the  mark  with  water,  noting  the  amount 
added.  Subtract  the  quantity  of  water,  iodin  solution,  and  the  starch  indicator 
added,  to  determine  the  quantity  of  the  water  titrated.  An  excess  of  iodin  is  re- 
quired to  produce  a  blue  color.  A  correction  is  obtained  by  adding  5  cc.  of  the 
starch  indicator  to  500  cc.  of  water  and  then  adding  N/100  iodin  until  the  color 
matches  that  of  the  sample  under  examination.  Correct  the  original  titration  by 
the  amount  of  iodin  used  in  the  blank. 


42  METHODS    OF  ANALYSIS  [Chap. 

38  FREE  CARBON   DIOXID.— TENTATIVE.  ' 

If  the  water  reacts  acid  to  phenolphthalein  and  alkaline  to  methyl  orange,  titrate 
100  cc.  with  N/20  sodium  carbonate  (free  from  bicarbonate)  until  the  solution  ia 
neutral  to  phenolphthalein.  The  number  of  cc.  used  multiplied  by  1.1  gives  the 
milligrams  of  free  carbon  dioxid  in  100  cc.     Express  results  in  milligrams  per  liter. 

39  CARBONIC  AND  BICARBONIC  ACIDS.— OFFICIAL. 

To  100  cc.  of  the  water  add  a  few  drops  of  phenolphthalein  and,  if  a  pink  color  is 
produced,  titrate  with  N/20  crystallized  potassium  hydrogen  sulphate  or  sulphuric 
acid,  adding  a  drop  every  2  or  3  seconds,  until  the  red  color  disappears.  Multiply 
the  burette  reading  by  the  factor  3  which  gives  the  milligrams  of  the  carbonic  acid 
ion  in  100  cc.  To  the  colorless  solution  from  this  titration,  or  to  the  original  solution 
if  no  color  is  produced  with  phenolphthalein,  add  1  or  2  drops  of  methyl  orange;  con- 
tinue the  titration  without  refilling  the  burette  and  note  the  total  reading.  If 
carbonic  acid  is  absent,  multiply  the  total  burette  reading  by  the  factor  3.05,  which 
gives  the  value  of  the  bicarbonic  acid  ion  in  milligrams  per  100  cc.  If  carbonic  acid  is 
present,  multiply  the  reading  with  phenolphthalein  by  2  and  subtract  from  the  total 
reading  of  the  burette.  Multiply  the  difference  by  3.05,  which  gives  the  bicarbonic 
acid  ion  in  milligrams  per  100  cc.     Express  results  in  milligrams  per  liter. 

Silica,  Iron,  Aluminium,  Calcium.  Strontium  and  Magnesium. 

40  silica.-official. 

Make  a  preliminary  examination,  using  100-250  cc.  of  water  to  determine  the 
approximate  quantity  of  calcium  and  magnesium  present,  in  order  to  ascertain 
the  quantity  of  water  to  be  evaporated  for  the  final  analysis. 

Evaporate  a  quantity,  usually  1-5  liters,  of  the  water  sufficient  to  yield  0.1-0.6 
gram  of  calcium  oxid  or  0.1-1  gram  of  magnesium  pyrophosphate.  Acidify  the 
water  with  hydrochloric  acid  and  evaporate  on  the  water  bath  to  dryness  in  a  plati- 
num dish;  continue  the  drying  for  about  an  hour.  Thoroughly  moisten  the  residue 
with  5-15  cc.  of  hydrochloric  acid  (1  to  1).  Allow  to  stand  10-15  minutes  and  add 
sufficient  water  to  bring  the  soluble  salts  into  solution.  Heat  on  the  steam  bath 
until  solution  of  the  salts  is  effected.  Filter  to  remove  most  of  the  silica  and  wash 
thoroughly  with  hot  water.  Evaporate  the  filtrate  to  dryness;  treat  with  5-10  cc. 
of  the  hydrochloric  acid  and  sufficient  water  as  above.  Heat,  filter,  and  wash 
thoroughly  with  hot  water.  Designate  the  filtrate  as  A .  Transfer  the  2  residues  to 
a  platinum  crucible,  ignite,  heat  over  a  blast  lamp  and  weigh.  Moisten  the  contents 
of  the  crucible  with  a  few  drops  of  water.  Add  a  few  drops  of  concentrated  sulphuric 
acid  and  a  few  cc.  of  hydrofluoric  acid  and  evaporate  on  the  water  bath  under  a  good 
hood.  Repeat  the  treatment  if  all  the  silica  is  not  volatilized.  Dry  carefully  on  a 
hot  plate,  ignite,  heat  over  a  blast  lamp,  and  weigh.  The  difference  between  the 
two  weights  'S  the  weight  of  the  silica.  The  residue  in  the  crucible  consists  of  alumin- 
ium and  iron  oxids.  The  weight  of  this  residue  is  added  to  that  of  the  total  alumin- 
ium and  iron  oxids  obtained  in  41 .  (If  the  above  residue  weighs  more  than  0.5  mg., 
barium  sulphate  may  be  found  here  when  barium  is  present  in  the  water.  If  so, 
make  the  necessary  correction  and  add  to  the  weight  of  the  total  iron  and  aluminium 
oxids  in  41 .) 

41  IRON  AND  aluminium.— OFFICIAL. 

Concentrate  A ,  under  40,  to  about  200  cc. ;  while  still  hot,  add  ammonium  hydroxid 
slowly  with  constant  stirring  until  alkaline  to  methyl  orange.  Boil,  filter,  and  wash 
2  or  3  times  with  hot  water.     Dissolve  the  precipitate  in  hot  hydrochloric  acid. 


IV]  WATERS  43 

Dilute  to  approximately  25  cc,  boil,  and  again  precipitate  with  ammonium  hydroxid; 
filter,  wash  thoroughly  with  hot  water,  dry,  ignite,  and  weigh  as  iron  and  aluminium 
oxids.  (In  the  presence  of  phosphoric  acid,  the  weight  of  this  residue  must  be  cor- 
rected for  the  phosphorus  pentoxid  equivalent  to  the  phosphoric  acid  found  in  51 , 
making  due  allowance  for  the  difference  in  the  volumes  of  the  water  used  for  these 
determinations.)     Designate  the  filtrate  as  B. 

IRON. 

42  Colorimelric  Method. 

(If  the  amount  of  iron  is  less  than  1  mg.) 

Fuse  in  a  platinum  crucible  the  ignited  precipitate  of  iron  and  aluminium 
oxids  with  fused  potassium  hydrogen  sulphate,  dissolve  in  water,  and  precipitate  the 
iron  and  aluminium  with  ammonium  hydroxid.  Dissolve  the  precipitate  on  the 
filter  paper  in  hydrochloric  and  nitric  acids,  dilute  the  solution,  add  ammonium 
sulphocyanate  solution  (1  to  20)  and  compare  the  color  developed  with  that  of 
calibrated  color  disks,  or  standards  containing  known  amounts  of  iron. 

43  Volumetric  Method. 

Fuse  in  a  platinum  crucible  the  residue  of  iron  and  aluminium  oxids  with  fused 
potassium  hydrogen  sulphate.  This  fusion  takes  but  a  few  minutes  and  must  not 
be  continued  beyond  the  time  actually  needed.  When  completed,  the  crucible 
is  set  aside  and  allowed  to  cool.  Add  dilute  sulphuric  acid  and  heat  the  crucible 
until  the  fused  mass  is  dissolved.  Evaporate  on  the  water  bath  as  far  as  possible; 
then  heat  gradually  until  copious  fumes  of  sulphuric  acid  are  given  off.  Dissolve 
in  water  and  allow  to  stand  on  the  water  bath.  Cool,  transfer  to  an  Erlenmeyer 
flask,  and  make  up  to  such  a  volume  that  the  solution  does  not  contain  more  than 
2.5%  of  free  sulphuric  acid.  Pass  hydrogen  sulphid  through  the  solution  to  reduce 
the  iron  and  precipitate  any  platinum  contaminating  the  residue  from  the  fusion. 
(Zinc  may  be  used  instead  of  hydrogen  sulphid  for  reducing  the  iron.)  Filter,  wash 
and  again  pass  hydrogen  sulphid  through  the  solution  to  be  certain  that  all  the  iron 
is  reduced.  Expel  the  hydrogen  sulphid  by  boiling,  at  the  same  time  passing  a 
current  of  carbon  dioxid  through  the  solution;  test  the  escaping  gas  with  lead  acetate 
paper  to  ascertain  the  complete  removal  of  hydrogen  sulphid.  When  hydrogen 
sulphid  has  been  removed  discontinue  boiling  and  let  the  flask  cool  somewhat  with- 
out discontinuing  the  current  of  carbon  dioxid.  Titrate  the  reduced  iron  with  a 
standard  permanganate  solution  (1  cc.  equivalent  to  1  mg.  of  Fe)  and  calculate  as 


44  '     ALUMINIUM.— OFFICIAL. 

In  the  absence  of  phosphates,  subtract  from  the  weight  of  iron  and  aluminium 
oxids,  under  41 ,  the  iron,  under  42  or  43,  calculated  to  oxid,  to  obtain  the  weight  of 
aluminium  o\id.     Calculate  to  aluminium. 

45  CALCIUM.— OFFICIAL. 

Concentrate  B,  under  41 ,  to  150-200  cc.  and  to  this  solution,  containing  not  more 
than  0.6  gram  of  calcium,  calculated  as  calcium  oxid,  or  1  gram  of  magnesium,  cal- 
culated as  magnesium  pyrophosphate,  add  1-2  grams  of  oxalic  acid  and  sufficient 
hydrochloric  acid  to  clear  the  solution.  Heat  to  boiling  and  neutralize  with  ammo- 
nium hydroxid,  stirring  constantly.  Add  ammonium  hydroxid  in  slight  excess  and 
alloi«'  to  stand  3  hours  in  a  warm  place.     Filter  off  the  supernatant  liquid  and  wash 


44  METHODS    OF    ANALYSIS  [Chap. 

the  precipitate  once  or  twice  by  decantation  with  1%  ammonium  oxalate  solution. 
Dissolve  the  precipitate  in  hydrochloric  acid,  dilute  to  100-200  cc,  add  a  little 
oxalic  acid,  and  precipitate  as  above.  After  standing  3  hours,  filter,  wash  with  the 
ammonium  oxalate  solution  as  above,  dry,  ignite,  heat  over  a  blast  lamp,  and  weigh 
as  calcium  and  strontium  oxids.  Subtract  from  this  weight,  the  weight  of  strontium 
oxid  equivalent  to  the  strontium  under  46.  The  difference  is  the  weight  of  calcium 
oxid.     Calculate  to  calcium.     Designate  the  filtrate  and  washings  as  C. 

As  a  check  on  the  calcium  oxid,  evaporate  to  dryness  the  filtrate  from  the  stron- 
tium nitrate  under  46,  beginning  with  "Filter,  wash  with  ether-alcohol  mixture, 
etc.,"  dissolve  the  calcium  nitrate  in  water,  precipitate  as  oxalate,  filter,  wash, 
ignite,  and  weigh  as  calcium  oxid. 

46  STRONTIUM.— TENTATIVE. 

Dissolve  the  oxids  under  45  in  dilute  nitric  acid  and  test  with  the  spectroscope  for 
strontium.  If  strontium  is  present,  transfer  the  nitric  acid  solution  to  a  small 
Erlenmeyer  flask.  Evaporate  nearly  to  dryness  over  a  low  flame  and  heat  in  an 
air  bath  at  150°-160°C.  for  1  or  2  hours  after  the  water  is  evaporated.  Break  up  the 
dried  material  with  a  stirring  rod,  add  10-15  cc.  of  a  mixture  of  equal  parts  of  absolute 
alcohol  and  ether  to  dissolve  the  calcium  nitrate.  Cork  the  flask  and  allow  to  stand 
with  frequent  shaking  for  2  hours  or  longer.  Decant  the  solution  through  a  5.5  cm. 
filter,  preserving  the  filtrate.  Wash  the  residue  several  times  by  decantation  with 
small  portions  of  ether-alcohol  solution.  Dry  the  residue  and  the  filter  paper  and 
wash  the  filter  paper  repeatedly  with  small  portions  of  hot  water,  collecting  the 
filtrate  in  the  flask  containing  the  main  portion  of  the  strontium  nitrate  residue. 
Add  1  or  2  drops  of  dilute  nitric  acid,  evaporate,  dry,  pulverize,  and  treat  with 
10-15  cc.  of  ether-alcohol  mixture  as  above.  Cork  the  flask  and  let  stand  about  12 
hours  with  occasional  shaking.  Filter,  wash  with  ether-alcohol  mixture  until  a  few 
drops  of  the  filtrate  evaporated  on  a  watch  glass  leave  practically  no  residue.  Dry 
the  paper  and  precipitate.  Dissolve  the  strontium  nitrate  in  a  few  cc.  of  hot  water. 
Add  a  few  drops  of  sulphuric  acid,  then  a  volume  of  alcohol  equal  to  the  volume  of 
the  solution  and  allow  to  stand  12  hours.  Filter,  ignite,  weigh  as  strontium  sulphate 
and  calculate  to  strontium.     Test  spectroscopically  for  absence  of  calcium. 

47  MAGNESIUM.— OFFICIAL. 

Concentrate  C,  under  45,  to  about  200  cc. ;  add  2-3  grams  of  diammonium  hydrogen 
phosphate  and  sufficient  hydrochloric  acid  to  clear  the  solution  when  the  arnmonium 
phosphate  is  all  dissolved;  disodium  hydrogen  phosphate  or  sodium  ammonium 
hydrogen  phosphate  may  be  used  instead  of  the  diammonium  hydrogen  phosphate. 
When  cold,  make  slightly  alkaline  with  ammonium  hydroxid,  stirring  constantly. 
Add  1-2  cc.  excess  of  ammonium  hydroxid  and  allow  to  stand  about  12  hours.  Filter 
off  the  supernatant  liquid  and  wash  3  or  4  times  by  decantation  with  a  solution  of 
2.5%  ammonium  hydroxid.  Dissolve  the  precipitate  in  hydrochloric  acid,  dilute  to 
about  150  cc,  add  a  little  diammonium  hydrogen  phosphate  and  precipitate  with 
ammonium  hydroxid  as  before.  Allow  to  stand  6-12  hours,  filter,  wai.?h  free  from 
chlorin,  ignite,  heat  over  a  blast  lamp,  and  weigh  as  magnesium  pyrophosphate. 
(Cf.  II,  16).     Calculate  to  magnesium. 

Sulphuric  Acid,  Sodium,  Potassium  and  Lithium. 

48  sulphuric  acid.— official. 

Make  a  preliminary  examination,  using  100-250  cc.  of  the  water  to  determine  the 
approximate  quantity  of  sulphates.     The  alkali  salts  present  can  be  approximated 


IV]  WATERS  45 

by  calculating  the  amount  of  sodium  necessary  to  combine  with  the  excess  of  acids 
(hydrochloric,  sulphuric,  and  bicarbonic)  over  the  calcium  and  magnesium. 

Take  a  quantity,  usually  1-5  liters,  of  the  water  suflficient  to  yield  not  more  than 
1  gram  of  barium  sulphate  and  not  more  than  0.5  gram  of  mixed  chlorids.  Acidify 
with  hydrochloric  acid,  evaporate  to  dryness  in  a  platinum  dish  and  remove  silica 
by  2  evaporations  as  under  40,  using  not  more  than  2  cc.  of  hydrochloric  acid  (1  to  1) 
for  the  final  solution.  Combine  the  filtrate  and  washings  from  the  silica  determi- 
nations, and  concentrate  to  about  150-200  cc.  Heat  to  boiling  and  precipitate  with 
alight  excess  of  10%  barium  chlorid  solution,  added  very  slowly  and  with  constant 
stirring.  Cover  and  allow  to  stand  on  the  steam  bath  about  12  hours.  Filter,  wash 
thoroughly  the  precipitate  of  barium  sulphate  with  hot  water,  dry,  ignite  over  a 
Bunsen  burner,  and  weigh. 

If  the  content  of  sulphate  in  the  sample  is  unusually  large  proceed  as  far  as  the 
concentration  of  the  silica  filtrates  as  directed  above.  Add  50  cc.  of  concentrated 
hydrochloric  acid,  heat  to  boiling  and  precipitate  with  barium  chlorid  solution  as 
before.  Evaporate  to  dryness,  wash  the  precipitate  repeatedly  by  decantation  and 
filter.  Complete  the  washing  of  the  precipitate;  ignite  and  weigh.  Calculate  to 
the  sulphuric  acid  ion.     Designate  the  filtrate  as  E. 


49 


SODroM,  POTASSIUM  AND  LITHIUM.— OFFICIAL. 


Evaporate  to  dryness £',  under  48,  in  a  platinum  dish  and  ignite  the  residue  to  faint 
redness  to  remove  all  traces  of  ammonium  salts.  Dissolve  the  residue  in  the  dish 
in  about  200  cc.  of  water  and  precipitate  with  milk  of  lime  or  a  solution  of  barium 
hydroxid.  Boil,  allow  to  stand  30  minutes,  and  filter  off  the  insoluble  magnesium 
hydroxid.  Thoroughly  wash  the  precipitate  with  hot  water  and  combine  the  filtrate 
and  washings.  If  the  precipitate  of  magnesium  is  large,  it  is  advisable  to  dissolve 
in  a  small  amount  of  hydrochloric  acid,  evaporate  to  dryness,  take  up  with  water, 
and  precipitate  as  before.  Concentrate  the  2  filtrates  and  washings  to  200-250  cc. 
Add  ammonium  hj'droxid  and  sufficient  ammonium  carbonate  solution  to  precipi- 
tate the  calcium  and  barium.  Allow  to  stand  on  a  steam  bath  1-2  hours.  Filter  off 
the  supernatant  liquid,  dissolve  the  precipitate  in  hydrochloric  acid,  reprecipitate  as 
above,  and  wash  thoroughly  with  hot  water.  Evaporate  the  combined  filtrates  and 
washings  to  dryness  and  drive  off  the  ammonium  salts  by  gentle  heat.  Treat  the 
residue  with  water;  filter  through  a  small  filter,  using  as  little  wash  water  as  possible; 
evaporate  to  a  small  volume  and  again  precipitate  with  1  or  2  drops  of  ammonium 
hydroxid  and  2  or  3  drops  of  ammonium  carbonate  and  oxalate.  If  any  precipitate 
appears  (which  is  usually  not  the  case)  filter  and  repeat  the  process.  Evaporate  the 
filtrate  to  dryness  and  drive  off  all  ammonium  salts  by  heating  in  platinum  to  faint 
redness.  Treat  the  residue  with  a  little  water;  filter  into  a  small  platinum  dish; 
add  a  few  drops  of  hydrochloric  acid  and  evaporate  to  dryness.  Dry  in  an  oven, 
heat  to  faint  redness,  cool  in  a  desiccator,  and  weigh  the  combined  chlorids  of  potas- 
sium, sodium,  and  lithium.  Repeat  the  heating  to  constant  weight,  (i).  Dissolve 
the  mixed  chlorids  in  hot  water;  filter,  and  wash.  Return  the  filter  paper  and  residue 
to  the  dish,  dry,  ignite,  and  weigh,  {y).  The  difference  between  (x)  and  {y)  is  the 
weight  of  the  mixed  chlorids. 

The  determination  of  lithium  is  then  made  according  to  the  method  of  Gooch.* 
Transfer  the  combined  chlorids  to  a  50-100  cc.  Erlenmeyer  flask  and  evaporate  the 
solution  nearly,  but  not  quite,  to  dryness.  Add  about  30  cc.  of  redistilled  amyl 
alcohol.  Connect  the  flask,  the  stopper  of  which  carries  a  thermometer,  using  a 
condenser  if  desired,  to  avoid  the  escape  of  the  irritating  vapor  of  the  amyl  alcohol, 
and  boil  until  the  temperature  rises  approximately  to  the  boiling  point  of  amyl  alco- 


46  METHODS   OF   ANALYSIS  [Chap. 

hoi  (130°C.)  to  remove  the  water.  Cool  slightly  and  add  a  drop  of  hydrochloric  acid 
to  convert  small  amounts  of  lithium  hydroxid  to  lithium  chlorid.  Connect  with  the 
condenser  and  repeat  the  boiling  until  the  temperature  reaches  the  boiling  point  of 
amyl  alcohol  to  again  drive  off  the  water.  The  content  of  the  flask  at  this  time  is 
usually  15-20  cc.  Filter  through  a  small  paper  or  a  Gooch  crucible  into  a  graduated 
cylinder  and  note  the  exact  quantity  of  the  filtrate,  which  determines  the  subsequent 
correction.  Wash  the  precipitate  with  small  quantities  of  amyl  alcohol.  Evapo- 
rate the  filtrates  and  washings  in  a  small  platinum  dish  to  dryness  on  the  steam  bath, 
dissolve  the  residue  in  water,  and  add  a  few  drops  of  sulphuric  acid.  Evaporate  on 
a  steam  bath  and  expel  the  excess  of  sulphuric  acid  by  heating  gently  over  a  Bunsen 
burner  until  the  carbonaceous  matter  is  completely  burned  off,  repeating  the  addi- 
tion of  a  few  drops  of  sulphuric  acid  if  necessary.  Cool  and  weigh  the  dish  and 
contents,  (x).  Dissolve  in  a  small  quantity  of  hot  water,  filter  through  a  small 
filter,  wash  and  return  filter  to  dish;  ignite  and  weigh,  (y).  The  difference  between 
(x)  and  iy)  is  the  weight  of  impure  lithium  sulphate. 

The  purity  of  the  lithium  sulphate  should  be  tested  by  adding  small  amounts  of 
ammonium  phosphate  solution  and  ammonium  hydroxid,  which  will  precipitate  any 
magnesium  previously  present  in  the  lithium  sulphate.  Any  precipitate  appearing 
after  standing  overnight  should  be  collected  on  a  small  filter,  ignited,  weighed  as 
magnesium  pyrophosphate,  calculated  to  sulphate  and  subtracted  from  the  weight 
of  the  impure  lithium  sulphate. 

From  this  weight  subtract  0.00113  gram  of  sodium  and  potassium  sulphates  for  every 
10  cc.  of  amyl  alcohol  filtrates,  exclusive  of  the  amyl  alcohol  used  in  washing  the 
residue,  on  account  of  the  solubility  of  sodium  and  potassium  chlorids  in  amyl  alco- 
hol.    Calculate  to  lithium  from  the  corrected  weight  of  lithium  sulphate. 

Dissolve  the  mixed  chlorids  from  the  flask  and  filter  with  hot  water,  evaporate 
to  dryness,  ignite  gently  to  remove  amyl  alcohol,  filter,  and  thoroughly  wash;  con- 
centrate the  filtrates  and  washings  to  25-50  cc.  Transfer  to  a  porcelain  dish,  add 
sufficient  platinic  chlorid  solution  [I,  40  (b)]  to  convert  sodium  and  potassium  to 
their  respective  double  chlorids  and  evaporate  to  dryness.  Treat  the  residue 
with  80%  alcohol,  filter,  and  wash  until  the  excess  of  platinic  chlorid  and  sodium 
platinic  chlorid  has  been  removed.  Dry  the  filter  and  precipitate,  dissolve  the 
residue  in  hot  water,  and  transfer  to  a  weighed  platinum  dish.  Evaporate  on  the 
steam  bath,  dry  for  30  minutes  in  the  oven  at  100°C.  and  weigh  as  potassium  platinic 
chlorid;  calculate  to  potassium  chlorid.  To  the  weight  of  potassium  chlorid  add 
0.00051  gram  for  every  10  cc.  of  amyl  alcohol  used  in  the  extraction  of  the  lithium 
chlorid,  which  corrects  for  the  solubility  of  the  potassium  chlorid  in  amyl  alcohol. 
Calculate  to  potassium. 

The  weight  of  sodium  chlorid  is  found  by  subtracting  the  combined  corrected 
weights  of  lithium  chlorid  and  potassium  chlorid  from  the  total  weight  of  the  3 
chlorids.     Calculate  the  sodium  chlorid  to  sodium. 

PHOSPHORIC  ACID.— OFFICIAL. 

50  REAGENTS. 

The  reagents  used  are  described  under  I,  7. 

51  DETERMINATION. 

Treat  500  cc.  of  the  water,  or  a  larger  amount  if  necessary,  with  about  10  cc.  of 
concentrated  nitric  acid  and  evaporate  in  a  porcelain  dish  nearly  to  dryness  to  drive 
off  hydrochloric  acid.  Treat  the  residue  with  water  and  filter,  if  necessary.  Add 
ammonium  hydroxid  to  alkalinity  and  then  just  enough  nitric  acid  to  restore  acidity. 


rV]  WATERS  47 

Add  some  solid  ammonium  nitrate  and  heat  in  the  water  bath  at  a  temperature  of 
45*-50°C.  Add  the  molybdate  solution  and  keep  at  the  above  temperature  for  30 
minutes.  The  yellow  precipitate  formed  at  this  point  appears  generally  only  in 
traces;  if  more  than  traces  are  present,  filter  and  wash  with  cold  water  until  entirely 
free  from  nitric  and  molybdic  acids.  Transfer  the  precipitate  and  filter  to  a  beaker, 
add  a  little  water,  and  beat  the  paper  and  contents  to  a  pulp.  Dissolve  the  yellow 
precipitate  in  a  small  amount  of  the  standard  potassium  hydroxid ;  add  phenolphtha!- 
ein  and  titrate  with  the  standard  acid.  From  the  data  so  obtained  calculate  the 
phosphoric  acid  ions  in  the  water  to  milligrams  per  liter. 

52  Manganese.  Iodin,  Bromin,  Arsenic  and  Boric  Acid. 
Evaporate  large  quantities  of  water  to  dryness,  after  the  addition  of  small  amounts 

of  solid  sodium  carbonate.  Boil  the  residue  thus  obtained  with  water,  transfer  to 
a  filter,  and  wash  thoroughly  with  hot  water.  Make  the  alkaline  filtrate  up  to  a 
definite  volume. 

MANGANESE.— OFFICIAL. 

53  REAGENTS. 

(a)  Dilute  nitric  acid  {1  to  1). 

(b)  0.2%  silver  nitrate  solution. 
(C)  Ammonium  persulphate. 

(d)  Standard  manganous  sulphate  solution. — Dissolve  0.2877  gram  of  pure  potas- 
sium permanganate  in  a  small  amount  of  water,  add  an  excess  of  sulphuric  acid, 
reduce  carefully  with  oxalic  acid  and  make  up  to  1  liter.  One  cc.  of  this  solution  is 
equivalent  to  0.1  mg.  of  manganese. 

54  DETERMINATION. 

Dissolve  the  insoluble  residue  under  52  in  an  excess  of  the  dilute  nitric  acid,  evap- 
orate to  dryness,  treat  with  water,  add  about  1  cc.  of  strong  nitric  acid  and  a  little 
of  the  silver  nitrate.  If  a  precipitate  of  silver  chlorid  appears,  add  more  of  the 
silver  nitrate  until  all  the  chlorin  is  precipitated.  Add  an  excess  of  about  10  cc.  of 
the  silver  nitrate  for  each  mg.  of  manganese  present  in  the  sample.  Filter,  add 
1  gram  of  ammonium  persulphate  to  the  filtrate,  and  place  the  beaker  or  flask  con- 
taining the  solution  on  the  steam  bath  until  a  pink  color  develops  (usually  about  20 
minutes).  Compare  the  color  developed  with  standards  similarly  prepared  by  treat- 
ing solutions  containing  known  amounts  of  the  standard  manganous  sulphate  with 
nitric  acid,  silver  nitrate,  and  ammonium  persulphate. 

IODIN  AND  BROMIN.— TENTATIVE. 

55  REAGENTS. 

(a)  10%  sodium  hydroxid  solution. 

(b)  Sulphuric  acid  {1  to  5). 

(C)  ;?%  potassium,  or  sodium  nitrite  solution. 

(d)  Carbon  disulphid.— Freshly  purified  by  distillation. 

(e)  Chlorin  water. — Saturated  and  freshly  prepared. 

56  DETERMINATION. 

Evaporate  to  dryness  an  aliquot  of  the  alkaline  filtrate  under  52,  add  2-3  cc.  of 
water  to  dissolve  the  residue  and  enough  95%  alcohol  to  make  the  percentage  of 
alcohol  about  90.  This  precipitates  the  chlorids.  Heat  to  boiling,  filter  and  repeat 
the  preceding  solution  and  precipitation  once  or  twice.     Add  2  or  3  drops  of  the 


48  METHODS    OF    ANALYSIS  [Chap. 

sodium  hydroxid  to  the  combined  alcoholic  filtrates  and  evaporate  to  dryness.  Dis- 
solve this  last  residue  in  2-3  cc.  of  water  and  repeat  as  above  described  the  precipi- 
tation with  alcohol,  heating,  and  filtering.  Add  a  drop  of  the  sodium  hydroxid  to 
this  alcoholic  filtrate  and  evaporate  to  dryness.  Dissolve  this  residue  in  a  little 
water,  acidify  with  the  sulphuric  acid,  using  3  or  4  drops  in  excess,  and  transfer  to 
a  small  flask.  Add  4  drops  of  the  potassium  nitrite  and  about  5  cc.  of  the  carbon 
disulphid.  Shake  until  all  the  iodin  is  extracted,  filter  off  the  acid  solution  from  the 
carbon  disulphid,  retaining  the  latter  in  the  flask.  Wash  the  flask,  filter  and  con- 
tents with  cold  water  and  transfer  the  carbon  disulphid  (containing  the  iodin  in 
solution)  to  a  Nessler  tube,  using  approximately  5  cc.  of  the  carbon  disulphid.  In 
washing  the  filter  make  the  contents  of  the  tube  up  to  definite  volume,  usually  12-15 
cc,  and  compare  the  color  with  that  of  other*  tubes  containing  known  amounts  of 
iodin  dissolved  in  carbon  disulphid.  Prepare  these  standard  tubes  by  treating 
measured  quantities  of  a  solution  of  known  potassium  iodid  content  as  described 
above.  Transfer  the  sample  and  standards,  from  which  the  iodin  has  been  removed, 
severally  to  small  flasks.  To  the  standards  add  definite  measured  quantities  of  a 
bromid  solution  of  known  strength,  and  to  each  of  the  flasks  containing  sample  and 
standards  add  5  cc.  of  purified  carbon  disulphid.  Add  the  saturated  chlorin  water, 
1  cc.  at  a  time,  shaking  after  each  addition  until  all  the  bromin  is  set  free.  (Avoid 
a  large  excess  of  chlorin,  since  a  bromo-chlorid  may  be  formed  which  spoils  the  color 
reaction.)  Filter  off  the  water  solution  from  the  carbon  disulphid  through  a  mois- 
tened filter,  wash  the  contents  of  the  filter  2  or  3  times  with  water,  and  then  transfer 
to  a  Nessler  tube  by  means  of  about  1  cc.  of  carbon  disulphid.  Repeat  this  extrac- 
tion of  the  filtrate  twice,  using  3  cc.  of  carbon  disulphid  each  time.  The  combined 
carbon  disulphid  extracts  usually  amount  to  11.5-12  cc.  Add  enough  carbon  di- 
sulphid to  the  tubes  to  bring  them  to  a  definite  volume,  usually  12-15  cc,  and  com- 
pare the  sample  with  the  standards.  In  some  cases  when  using  this  method  near  its 
upper  limit  the  amounts  of  carbon  disulphid  recommended  do  not  extract  all  the 
bromin.  In  these  cases,  make  1  or  2  extra  e.xti'actions  with  carbon  disulphid,  trans- 
fer the  extracts  to  another  tube,  and  compare  the  color  with  some  of  the  lower 
standards  and  add  the  readings  thus  obtained  to  the  others. 

Results  closely  approximating  the  true  values  for  iodin  and  bromin  can  be  ob- 
tained on  most  samples  by  omitting  the  extractions  with  alcohol  given  above  and 
by  comparing  the  color  of  the  carbon  disulphid  solutions  directly  in  the  extraction 
flasks,  thus  shortening  the  method. 

ARSENIC-OFFICIAL. 
57  REAGENTS. 

(a)  Zinc,  arsenic-free. 

(b)  Sulphuric  acid  (1  to  5),  arsenic-free. 

(C)  Standard  arsenious  oxid  solution. — Dissolve  0.0132  gram  of  pure  arsenious 
oxid  in  100  cc.  of  water  containing  about  50  mg.  of  sodium  carbonate.  One  cc.  of 
this  solution  is  equivalent  to  0.1  mg.  of  As. 


DETERMINATION. 


58 

Evaporate  to  dryness  an  aliquot  of  the  alkaline  filtrate  under  52.  Acidify  with 
the  sulphuric  acid  and  subject  to  the  action  of  the  zinc  and  the  sulphuric  acid  in  a 
Marsh-Berzclius  apparatus.  Compare  the  mirror  obtained  with  a  mirror  prepared 
from  an  arsenious  oxid  solution  of  known  strength.     Calculate  to  the  arsenic  acid 


rVJ  WATERS  49 

BORIC  ACID.— OFFICIAL. 
(Glassware  containing  boron  must  not  be  used  in  this  determination.) 

59  DETERMIN.\TIOX. 

Qualitative  test. — Evaporate  to  dryness  a  part  of  the  alkaline  filtrate  under  52, 
treat  with  1-2  cc.  of  water,  and  slightly  acidify  with  dilute  hydrochloric  acid  (1  to  1). 
Add  about  25  cc.  of  95%  alcohol,  boil,  filter,  and  repeat  the  extraction  of  the  residue. 
Make  the  filtrate  slightly  alkaline  with  sodium  hydroxid  solution  and  evaporate 
to  dryness.  Add  a  little  water,  slightly  acidify  with  dilute  hydrochloric  acid,  and 
place  a  strip  of  turmeric  paper  in  the  liquid.  Evaporate  to  dryness  on  the  steam 
bath  and  continue  the  heating  until  the  turmeric  paper  is  dry.  If  boric  acid  is 
present  the  turmeric  paper  takes  on  a  cherry-red  color.  As  a  confirmatory  test, 
apply  a  drop  of  dilute  ammonium  hydroxid  to  the  reddened  paper,  and  a  dark 
olive  color  will  be  due  to  boric  acid. 

Quantitative  test. — It  is  not  usually  necessary  to  determine  boric  acid  quantita- 
tively.    However,  if  it  is  necessary,  the  Gooch  method^  is  used. 

60  METHOD    OF   REPORTING   RESULTS.— TENTATIVE. 

Report  the  bases  and  acids  as  positive  and  negative  ions  in  milligrams  per  liter, 
except  in  the  case  of  silica,  which  report  as  such  without  considering  how  much  is 
present  as  the  silicic  acid  ion  and  how  much  as  free  silica.  Report  iron  and  alumin- 
ium together  when  present  in  unimportant  quantities,  and  in  calculations  consider 
it  as  iron.  When  iron  and  aluminium  are  present  in  larger  quantities  make  the 
separation  and  report  each  separately. 

In  calculating  the  hypothetical  combinations  of  acid  and  basic  ions  join  sodium 
to  nitrous,  nitric,  metaboric  and  arsenic  acids;  potassium  to  iodin  and  bromin; 
calcium  to  phosphoric  acid.  Assign  the  residual  basic  ions  in  the  following  order; 
ammonium,  lithium,  pota.ssium,  sodium,  magnesium,  calcium,  strontium,  manganese, 
iron  and  aluminium — to  the  residual  acid  ions  in  the  following  order:  Chlorin, 
sulphuric  acid  ion,  carbonic  acid  ion,  and  bicarbonic  acid  ion.  In  case  the  bicar- 
bonic  acid  ion  is  not  present  in  a  sufficient  quantity  to  join  with  all  the  calcium, 
the  residual  calcium  is  joined  to  silica  to  form  calcium  silicate,  and  manganese,  iron, 
and  aluminium  are  calculated  to  the  oxids  MusO^,  Fe20j,  and  AI2O3,  respectively. 

INDUSTRIAL  WATER. 

61  SOLIDS  IN   SOLUTION.— OFFICIAL. 
Determine  as  directed  under  7. 

62  CHLORIN.— OFFICIAL, 
Determine  as  directed  under  19. 

63  COMBINED  CARBONIC  AND  BICARBONIC  ACIDS.-OFFICLAL. 
Determine  as  directed  under  39. 

64  NITRATES.-OFFICLAL. 
Determine  as  directed  under  15  or  17. 

65  SILICA.-OFFICLAL. 

Determine  as  directed  under  40.  Generally  one  evaporation  with  hydrochloric 
acid  for  removal  of  silica  is  sufficient. 


50  METHODS    OF    ANALYSIS  [Chap. 

Q6  IRON  AND  ALUMINIUM.— OFFICIAL. 

Determine  as  directed  under  41 . 

67  CALCIUM.— OFFICIAL. 

If  no  phosphoric  acid  is  present,  concentrate  the  filtrate  from  the  determination 
of  iron  and  precipitate  with  ammonium  hydroxid  and  oxalate  as  directed  under  45. 
Usually  one  precipitation  is  sufficient. 

$8  MAGNESIUM.— OFFICIAL. 

Determine  as  directed  under  47. 

69  SULPHURIC  ACID  AND  ALKALIES. -OFFICIAL. 

Follow  the  methods  described  under  48  and  49.  Generally,  however,  for  tech- 
nical purposes  it  is  sufficiently  accurate  to  determine  the  acids  and  the  bases, 
except  sodium  and  potassium,  and  then  to  calculate  the  excess  of  acid  over  basic 
ions  to  the  sodium  salt,  and  state  the  alkali  thus  found  as  sodium  and  potassium  by 
difference. 

70  TEMPORARY  HARD  NESS.  7— TENTATIVE. 

The  difference  between  the  alkalinity  after  boiling,  74,  and  the  alkalinity  before 
boiling,  72,  is  the  temporary  hardness  in  parts  per  million  of  calcium  carbonate. 

ALKALINTTY-Before  BoiUng. 

71  REAGENTS. 

(a)  N /50  sulphuric  acid. 

(b)  Erythrosin  indicator. — Dissolve  0.1  gram  of  the  sodium  salt  in  1  liter  of  water. 
(C)  Chloroform. — Neutral  to  erythrosin. 


72 


DETERMINATION. 


Measure  100  cc.  of  the  water  into  a  250  cc.  white,  glass-stoppered  bottle,  add  2.5  cc. 
of  the  erythrosin  and  5  cc.  of  the  chloroform,  add  X/50  sulphuric  acid  in  small  quanti- 
ties, shaking  the  bottle  vigorously  after  each  addition  of  the  acid.  The  rose  color 
gradually  disappears  and  is  finally  discharged  by  1  or  2  drops  of  the  acid.  A  white 
paper  held  back  of  the  bottle  facilitates  the  detection  of  the  end  point.  Multiply 
the  number  of  cc.  of  N/50  sulphuric  acid  used  by  10  to  obtain  the  number  of  parts  per 
million  of  alkalinity  in  terms  of  calcium  carbonate. 


ALKALINTTY-After  BoUing 

73 

REAGENTS. 

Described  under  71 . 

74 

DETERMINATION. 

Boil  100  cc.  of  the  water  in  a  porcelain  dish  gently  for  30  minutes.  Cool,  transfer 
to  a  100  cc.  volumetric  flask  and  fill  to  the  mark  with  recently  boiled  and  cooled 
water.  Filter  through  a  dry  paper  and  determine  the  alkalinity  of  the  filtrate  as 
directed  under  72,  making  the  proper  calculation  for  the  aliquot  employed  and  cal- 
culating in  terras  of  calcium  carbonate  the  parts  per  million  of  alkalinity  after 
boiling. 


IV]  WATERS  51 

TOTAL   HARDNESS."— TENTATIVE. 

75  REAGENTS. 

(a)  Soda  reagent. — Prepare  a  N/10  alkali  solution,  using  equal  parts  of  sodium 
hydroxid  and  sodium  carbonate.  Standardize  the  solution  by  titration  against 
N/20  sulphuric  acid,  using  erythrosin  as  indicator. 

76  DETERMINATION, 

Add  sufficient  N/20  sulphuric  acid  to  200 cc.  of  the  sample  to  neutralize  the  alkalin- 
ity, the  amount  required  for  this  purpose  being  calculated  from  the  results  obtained 
as  directed  under  72.  Concentrate  to  100  cc,  add  25  cc.  of  the  soda  reagent,  and 
again  boil  down  to  100  cc,  using  a  porcelain,  silver,  or  platinum  dish.  Cool,  rinse 
into  a  200  cc.  volumetric  flask  and  dilute  to  200  cc.  with  freshly  boiled  and  cooled 
water.  Filter  through  a  dry  paper,  reject  the  first  50  cc.  of  the  filtrate,  and  titrate 
100  cc.  of  the  filtrate,  using  N/20  sulphuric  acid  and  chloroform  with  erythrosin  as 
indicator,  as  directed  under  72.  Calculate  the  total  hardness  by  the  following 
formula:  H  =  12.5  (S-2N)  in  which 

H  =  total  hardness  expressed  as  parts  per  million  of  calcium  carbonate. 

S  =  number  of  cc.  of  N/20  sulphuric  acid  equivalent  to  the  25  cc.  of  the  soda 
reagent  used. 

N  =  number  of  cc.  of  N/20  sulphuric  acid  used  in  titrating  back  the  excess  of 
the  soda  reagent. 

77  PERMANENT  OR  NON-CARBONATE  HARDNESS.— TENTATIVE. 

The  difference  between  the  alkalinity  before  boiling  72  and  the  total  hardness  76 
is  the  permanent  or  non-carbonate  hardness  expressed  as  parts  per  million  of  cal- 
cium carbonate. 

IRRIGATING  WATER. 

78  GENERAL  METHODS.— OFFICIAL. 

Determine  the  solids  in  solution,  chlorin,  carbonic  and  bicarbonic  acids,  sulphuric 
acid,  calcium  and  magnesium  as  directed  under  7,  19,  39,  48,  45,  and  47  respec- 
tively. To  make  the  hypothetical  combination,  calculate  calcium  and  magnesium 
to  the  acid  ions  in  the  following  order:  bicarbonic,  sulphuric  and  chlorin.  Then 
calculate  the  remaining  acid  ions,  including  carbonic,  to  the  corresponding  salts  of 
sodium. 

BLACK  ALKALI.— OFFICIAL. 

79  REAGENTS. 

(a)  N'/50  sodium  carbonate. — One  cc.  of  this  solution  is  equivalent  to  0.00106 
gram  of  sodium  carbonate. 

(b)  N/50  sulpJmric  acid. — One  cc.  of  this  solution  is  equivalent  to  0.0010  gram  of 
calcium  carbonate  or  0.00136  gram  of  calcium  sulphate. 

(C)  Enjihrosin  indicator. — Dissolve  0.25  gram  of  the  sodium  salt  in  1  liter  of  water, 
(d)  Chloroform. — Neutral  to  erythrosin. 

80  DETERMINATION. 

Transfer  200  cc.  of  the  water  to  a  platinum  or  silver  dish,  add  50-100  cc.  of  N/50 
sodium  carbonate,  according  to  the  amount  of  soluble  salts  of  calcium  and  magnesium 
present,  and  evaporate  to  dryness.  Rub  up  the  residue  with  carbon  dio-xid-free 
water. 


52  METHODS    OF   ANALYSIS 

For  this  purpose  distilled  water  should  be  vigorously  boiled  until  approximately 
one  third  of  the  original  volume  is  evaporated,  then  cooled  and  stoppered.  An 
ordinary  laboratory  wash  bottle  should  not  be  used  to  transfer  the  residue,  as  the 
carbon  dioxid  from  the  breath  of  the  operator  is  sufficient  to  vitiate  the  results. 

Transfer  to  a  100  cc.  graduated  flask,  make  up  to  the  mark,  shake  thoroughly,  and 
allow  to  stand  until  clear  (12-15  hours).  Remove  50  cc.  of  the  clear,  supernatant 
liquid,  equivalent  to  one  half  of  the  original  quantity  of  water  and  sodium  carbonate 
added,  and  transfer  to  a  stoppered  titrating  bottle,  of  250  cc.  capacity,  of  clear  glass 
without  any  tinge  of  pink.  Add  5  cc.  of  the  chloroform  and  1  cc.  of  the  erythrosin 
and  titrate  with  the  standard  acid  until  the  color  disappears.  Shake  the  solution 
vigorously  after  each  addition  of  the  acid;  the  chloroform  produces  a  milkj^  appear- 
ance which  makes  the  reading  of  the  end  point  sharp  and  certain. 

(1)  If  less  sulphuric  acid  is  required  than  is  equivalent  to  one  half  of  the  sodium 
carbonate  added,  due  to  some  of  the  sodium  carbonate  reacting  with  soluble  salts  of 
calcium  and  magnesium,  the  solution  originally  contained  no  black  alkali  in  excess 
but  rather  an  excess  of  the  so-called  permanent  or  non-carbonate  hardness.  It  is 
customary  to  express  the  hardness  in  terms  of  calcium  carbonate  or  calcium  sul- 
phate. With  irrigating  waters  the  latter  form  is  to  be  preferred.  Therefore,  the 
difference  between  the  number  of  cc.  of  the  sulphuric  acid  required  and  one  half  of 
the  number  of  cc.  of  the  sodium  carbonate  added  multiplied  by  the  factor  0.00136 
gives  the  equiA^alent  of  calcium  sulphate  in  100  cc.  of  the  water. 

(2)  If  more  sulphuric  acid  is  required  than  that  equivalent  to  one  half  of  the 
sodium  carbonate  added,  black  alkali  was  originally  present  in  the  solution  and  the 
difference  in  cc.  multiplied  by  the  factor  0.00106  gives  the  black  alkali  in  terms  of 
sodium  carbonate  in  100  cc.  of  water. 

BIBLIOGRAPHY. 

1  Fresenius.  Quantitative  Chemical  Analysis.  Revised  and  amplified  trans- 
lation of  the  6th  German  ed.,  1906,  2:  204. 

2  Ber.,  1888,  21:  2843;  Rept.  Mass.  State  Board  of  Health,  1890,  2:  722. 

»  J.  Am.  Chem.  Soc,  1911,  33:  362;  Standard  Methods  of  Water  Analysis.  Am. 
Pub.  H.  Assoc,  2nd  ed.,  1912,  pp.  61  and  62. 

«  Sutton.     Volumetric  Analysis,  10th  ed.,  p.  303;    Analyst,  1901,  26:  141, 

5  Am.  Chem.  J.  1887,  9:  33;  U.  S.  Geol.  Surv.  Bull.  422,  175. 

«Am.  Chem.  J.  1887,9:  23. 

^  Standard  Methods  of  Water  Analysis.  Am.  Pub.  H.  Assoc,  2nd  ed..  1912.  dd. 
36  and  37.  >  ,         ,  ff 

» Ibid,  pp.  40  and  41. 


i 


V.    TANNING  MATERIALS.— TENTATIVE. 
EXTRACTS. 

1  PREPARATION  OF  SOLUTION. 

(a)  Solid  extracts. — Grind  solid  extracts  in  a  large  porcelain  mortar,  so  that  the 
material  will  pass  through  a  10  mesh  sieve,  mix  thoroughly  and  weigh  out  a  quantity 
containing  3.75-4.25  grams  of  tannin.  This  shouldbedone  as  rapidly  as  possible  to 
avoid  change  in  moisture  content.  Pour  into  100  cc.  of  water  at  85''C.,  place  on  a 
steam  bath  and  stir  until  a  homogeneous  solution  is  obtained.  Transfer  to  a  1  liter 
flask  with  800  cc.  of  water  at  85°C.     Cool  rapidly  to  20°C.  and  make  up  to  1  liter. 

(b)  Fluid  extracts. — Allow  fluid  extracts  to  come  to  room  temperature  and  mix 
thoroughly.  Weigh  out  rapidly  a  quantity  containing  3.75-4.25  grams  of  tannin. 
Dissolve  by  washing  into  a  1  liter  flask  with  900  cc.  of  water  at  85°C.  Cool  rapidly 
to  20°C.  and  make  up  to  1  liter  at  20°C. 

After  the  preparation  of  the  solutions,  proceed  at  once  with  the  analj'sis. 

2  TOTAL  SOLIDS. 

Thoroughly'  mix  the  prepared  solution,  pipette  at  once  100  cc.  into  a  tared  flat- 
bottomed  glass  dish,  2|-3  inches  in  diameter,  and  (1)  evaporate  and  dry  for  16  hours 
in  a  combined  evaporator  and  dryer'  at  98°-100°C. ;  or,  (2)  after  evaporating  on  the 
steam  bath,  dry  for  12  hours  on  the  bottom  of  a  water  oven  at  98°-100°C.  Remove 
immediately  to  desiccators  containing  sulphuric  acid  (place  no  more  than  2  dishes  in 
1  desiccator)  and  weigh  rapidlj'  when  cooled.  Calculate  the  percentage  of  total 
solids. 

SOLUBLE  SOLIDS. 

3  PREPARATION   OF  FILTER. 

The  kaolin  used  should  be  neutral  to  phenolphthalein  and  should  not  yield  more 
than  1  mg.  of  soluble  solids  per  100  cc.  of  filtrate  of  a  1%  suspension  after  an  hour's 
digestion  at  20°C.  Dry  on  a  water  bath  and  preserve  in  a  tightly  stoppered  bottle. 
Add  about  75  cc.  of  the  solution,  as  prepared  under  1 ,  to  1  gram  of  the  kaolin  in  a 
beaker.  Stir  and  pour  immediately  into  a  single,  15  cm.  No.  590,  S.  &  S.  folded 
filter.  Return  the  filtrate  to  the  paper  when  approximately  25  cc.  have  run  through, 
repeat  the  operation  for  an  hour,  thus  transferring  all  the  kaolin  to  the  paper.  At 
the  end  of  an  hour,  discard  the  solution  on  the  filter  by  siphoning  it  off,  disturbing 
the  kaolin  as  little  as  possible. 

4  DETERMINATION. 

Bring  about  150  cc.  of  the  original  solution,  as  prepared  under  1 ,  to  exactly  20°C. 
Fill  the  filter,  prepared  as  under  3,  with  this  solution  and  discard  the  filtrate  until 
it  runs  through  clear.  Keep  the  filter  full,  the  temperature  of  the  filtering  solution 
at  20°-25°C.,  and  the  funnel  and  receiving  vessel  covered.  Pipette  at  once  100  cc.  of 
the  clear  filtrate  into  a  tared  dish,  evaporate  and  dry  as  directed  under  2.  Calculate 
the  percentage  of  soluble  solids. 

53 


54  METHODS    OF    ANALYSIS  [Chap. 


5  INSOLUBLE  SOLIDS. 

The  difference  between  the  percentage  of  the  total  solids  and  the  percentage  of 
soluble  solids  is  the  percentage  of  the  substance  insoluble  in  water  at  20''-25°C. 

NONTANNINS. 

6  REAGENTS. 

Hide  powder. — This  should  be  of  woolly  texture,  well  delimcd,  and  10  grams  of  the 
water-free  powder  should  require  12-13  cc.  of  N/10  sodium  hydroxid  to  neutralize  it. 

Calculate  the  amount  of  air-dry  hide  powder  which  will  be  required  for  the  number 
of  determinations  to  be  made,  on  a  basis  of  13  grams  of  air-dry  hide  powder  for 
each  determination.  Increase  this  calculated  amount  by  35  grams  of  dry  hide 
powder  to  provide  a  sufficient  amount  for  all  the  determinations. 

Thoroughly  digest  the  total  amount  of  hide  powder  with  10  times  its  weight  of 
water.  Then  for  each  gram  of  the  hide  powder,  so  digested,  add  1  cc.  of  3%  chrome 
alum  solution;  and  either  agitate  frequently  for  several  hours  and  let  stand  overnight 
or  agitate  in  some  form  of  mechanical  shaker  for  an  hour.  Transfer  to  a  strong 
linen  filter  and  squeeze  thoroughly.  Remove  from  the  filter  and  digest  for  15  minutes 
with  a  quantity  of  water  equivalent  to  15  times  the  weight  of  the  dry  hide  powder 
employed.  Filter  and  squeeze  to  approximately  73%  of  water,  using  a  press  if 
necessary.  Very  strong  pressure  is  required  to  reduce  the  water  content  below 
70%.  Repeat  the  digestion  and  filtration  3  times.  Determine  moisture  in  20  grams 
of  the  squeezed  hide  powder  as  directed  under  2. 

7  DETERMINATION. 

Place  46  grams  of  the  wet  hide  powder  in  a  suitable  container  of  about  300  cc. 
capacity,  add  200  cc.  of  the  tanning  solution,  as  prepared  under  1,  and  shake  for  10 
minutes  in  a  mechanical  shaker.  Squeeze  immediately  through  linen,  add  2  grams 
of  kaolin,  as  used  under  3,  to  the  filtrate  which  contains  the  nontannins,  stir,  and 
filter  through  a  single,  folded  18.5  cm.  filter  paper  (No.  IF.  Swedish,  preferred), 
refiltering  until  the  filtrate  is  clear.  The  filtrate  should  give  no  precipitate  with  a 
gelatin-salt  solution  (1%  gelatin  and  10%  salt).  Pipette  100  cc.  of  the  filtrate  into 
a  tared  dish  and  evaporate  as  directed  under  2.  Correct  the  weight  of  the  nontannin 
residue  for  the  dilution  caused  by  the  water  retained  in  the  wet  hide  powder.  Cal- 
culate the  percentage  of  nontannins. 

8  TANNIN. 

The  difference  between  the  percentage  of  the  solu})le  solids  and  the  percentage 
of  nontannins  is  the  percentage  of  tannin. 

DETECTION   OF  SULPHITE-CELLULOSE. 

9  REAGENTS. 

Siilphile-celtulose  solution. — Dissolve  0.5  gram  of  the  total  solids,  derived  from 
sulphite-cellulose,  in  1  liter  of  water.and  add  sufficient  tanning  material,  free  from 
sulphite-cellulose,  to  give  a  concentration  of  3.75-4.25  grams  of  tannin  per  liter. 

10  DETERMINATION. 

Place  5  cc.  of  the  tanning  solution,  prepared  as  under  1 ,  in  a  test  tube;  add  0.5  cc. 
of  anilin  and  shake  well;  then  add  2  cc.  of  concentrated  hydrochloric  acid  and  mix 
again.     Compare  the  precipitate  formed  with  that  produced  when  the  above  sul- 


V]  TANNING   MATERIALS  55 

phite-cellulose  solution  is  similarly  treated.  Sulphite-cellulose  is  held  to  be  present, 
in  the  predetermined  absence  of  the  synthetic  tanning  material,  Neradol-D,  if  the 
precipitates  are  approximately  equivalent  in  amount. 

LIQUORS. 

11  PREPARATION  OF  SOLUTION. 

Dilute  the  liquor  with  water  at  room  temperature  to  contain  approximately  0.7 
gram  of  solids  in  100  cc.  of  solution.  If  the  liquor  does  not  give  a  proper  solution 
with  water  at  room  temperature,  it  may  be  diluted  with  water  at  80°C.,  and  then 
cooled  rapidly  to  20''C. 

12  TOTAL  SOLIDS. 
Proceed  as  directed  under  2. 

13  SOLUBLE  SOLIDS. 
Proceed  as  directed  under  4. 

14  NONTANNINS. 

Proceed  as  directed  under  7,  using  the  amount  of  wet  chromed  hide  powder  which 
will  give  the  ratio  between  the  tannin  and  hide  powder  shown  in  the  following  table: 


TANNIN  RANGE  PER 

100  cc. 

DRT  HIDE  POWDER 
PER  200  CC. 

gram 

0.35—0.45 
0.25—0.35 
0.15—0.25 
0.00—0.15 

grams 

9.0—11.0 
6.5—  9.0 
4.0—  6.5 
0.0-  4.0 

TOTAL  ACIDITY. 

1 5  REAGENTS. 

(a)  Hematin  solution.— Digest  0.5  gram  of  hematin  in  100  cc.  of  cold  neutral  95% 
alcohol. 

(b)  Gelatin  solution. — Dissolve  10  grams  of  gelatin  in  hot  water,  cool,  add  25  cc.  of 
95%  alcohol  and  dilute.  If  the  gelatin  solution  is  acid  or  alkaline,  neutralize  with 
N/10  sodium  hydroxid  or  N/10  acetic  acid,  respectively,  using  hematin  solution  as 
indicator  and  make  up  to  1  liter. 

(C)  Kaolin. — Digest  with  dilute  hydrochloric  acid;  wash  and  dry  as  under  3. 
(d)  N/IO  sodium  hydroxid. 

16  DETERMINATION. 

Add  25  cc.  of  the  gelatin  solution  to  25  cc.  of  the  tanning  liquor  in  a  stoppered 
cylinder,  dilute  with  water  to  250  cc,  add  15  grams  of  the  kaolin  and  shake  vigorously. 
Allow  to  settle  for  at  least  15  minutes,  remove  30  cc.  of  the  supernatant  liquid,  dilute 
with  50  cc.  of  water  and  titrate  with  N/10  sodium  hydroxid,  using  the  hematin  solu- 
tion as  indicator.  Each  cc.  of  N/10  sodium  hj'droxid  is  equivalent  to  0.2  %  acid, 
calculated  as  acetic,  in  the  liquor. 


56 


METHODS    OF    ANALYSIS 


[Chap. 


17 


RAW  AND  SPENT  MATERIALS. 

(Under  raw  materials  are  included  woods,  barks,  leaves,  etc.) 
MOISTITRE  IN  SAMPLE  AS  RECEIVED. 


Cut  or  break  up  large  pieces  and  mix  the  sample  rapidly  to  avoid  change  in  mois- 
ture content.  Dry  as  directed  under  2,  a  suitable  weighed  quantity,  dependent  upon 
the  physical  condition  and  moisture  content  of  the  sample. 

18  PREPARATION  OF  SAMPLE. 

Dry  the  remainder  of  the  sample  at  a  temperature  not  above  60°C.  and  grind  to 
pass  through  a  20  mesh  sieve. 

19  MOISTURE  IN  PREPARED  SAMPLE. 

Take  10  grams  of  the  sample  prepared  in  1 8,  dry  as  directed  under  2,  and  calculate 
all  results  to  an  "as  received",  "air  dry",  or  "moisture  free"  basis  as  desired. 

20  EXTRACTION. 


FIG.  4.    METAL  EXTRACTOR  USED  FOR  EXTRACTING  TANNING  MATERIALS. 
(For  spent  materials  approximate  the  follov/ing  quantities  as  closely  as  possible.) 

Place  a  quantity  of  the  dried  sample,  containing  3.75-4.25  grams  of  tannin,  in  a 
beaker  and  wet  thoroughly  with  hot  water.  Place  a  perforated  porcelain  plate  in 
a  tin-lined  copper  extractor  of  the  general  form  shown  in  Fig.  4,  and  on  the  plate 
place  a  layer  of  cotton  and  wet  thoroughly  with  water.  Connect  the  extractor  with 
an  800  cc.  Erlenmeyer  flask  (G),  open  the  stock-cock  (E)  and  close  the  outlets  (C) 
and  (D).  Pour  into  the  extractor  the  material  to  be  extracted,  washing  it  into  the 
extractor  with  hot  water.  Return  the  percolate  through  the  extractor  until  it  is 
practically  clear.  Place  a  layer  of  cotton  on  top  of  the  material.  Close  the  stop- 
cock (E),  connect  with  an  800  cc.  Erlenmeyer  flask  containing  about  650  cc.  of  water, 
connect  (D)  by  a  delivery  tube  wuth  a  liter  graduated  collecting  flask,  return  the 
total  percolate  to  the  extractor  and  connect  by  means  of  the  metal  cap  (B)  with  a 
block  tin  condenser  (A)  in  such  a  way  that  the  condensate  will  drip  upon  the  layer 
of  cotton.  Boil  the  water  in  the  flask,  and  collect  400-500  cc.  of  percolate  from  the 
side  tube  (D).  Open  the  stop-cock  (E)  and  close  the  side  tube  (D),  add  water  to  the 
flask  (G),  if  necessary,  until  it  contains  about  200  cc.  Continue  the  extraction  with 
water  at  steam  heat,  allowing  the  percolate  to  run  back  into  the  boiling  flask.     Re- 


V]  TANNING  MATERIALS  57 

peat  with  2  successive  portions  (150-250  cc.  each)  of  water  for  a  total  of  14  hours, 
heating  at  such  a  rate  that  approximately  330  cc.  of  water  will  be  condensed  per 
hour.  Combine  all  the  extracts  in  the  graduated  liter  flask  in  which  the  first  per- 
colate was  received.    Heat  to  80°C.,  cool,  and  make  up  to  the  mark. 

21  ANALYSIS  OF  THE  EXTRACT. 

Proceed  as  directed  under  2—8,  inclusive.  If  more  dilute  solutions  than  the 
directions  specify  are  employed  in  the  determination  of  nontannins,  the  amount  of 
hide  powder  used  is  reduced,  as  directed  under  14. 

BIBLIOGRAPHY. 
1  J.  Am.  Leather  Chem.  Assoc,  1906, 1:  32. 


VI.  LEATHERS.— TENTATIVE. 
VEGETABLE  TANNED  LEATHER. 

1  PREPARATION  OF  SAMPLE. 

Grind  the  sample,  without  undue  heating,  and  pass  through  a  10  mesh  sieve.  The 
ground  sample  must  not  contain  hard  lumps.  Plane  heavily  greased  leathers  (con- 
taining more  than  20  %  fat)  into  very  thin  shavings.  Spread  out  the  prepared  sample 
an!  allow  it  to  return  to  atmospheric  moisture  condition;  mix  thoroughly,  and 
place  in  tightly  covered  containers. 

2  MOISTURE. 

Place  10  grams  of  the  sample,  as  prepared  under  1 ,  in  a  tared,  wide,  shallow,  weigh- 
ing bottle  (or  a  similar  dish  which  can  be  covered  tightly),  and  dry  in  a  water  oven 
for  15  hours  at  98^-100°C.  Cover  the  weighing  bottle,  cool  in  a  desi  cator  containing 
sulphuric  acid,  and  weigh.  The  moisture  present  in  the  leather  as  received  may  be 
determined  by  cutting  it  quickly  into  small  pieces  and  drying  without  grinding  as 
directed  above. 

3  TOTAL  ASH. 

Incinerate  slowly  5  grams  of  the  sample,  as  prepared  under  1 ,  at  a  dull  red  heat. 
If  difficulty  is  experienced  in  burning  off  the  carbon,  leach  the  residue  with  hot 
water,  filter  on  an  ashless  filter,  dry  and  ignite  the  filter  and  residue,  add  the  filtrate, 
evaporate  to  dryness  and  ignite.  Cool  in  a  desiccator  containing  sulphuric  acid  and 
weigh. 

The  ash  may  be  examined  for  acids  and  bases  by  any  suitable  method.  Alumin- 
ium, magnesium,  sodium,  barium,  calcium  and  lead  are  the  bases,  and  hydrochloric 
and  sulphuric  acids  are  the  acids  which  it  may  be  necessary  to  determine. 

4  INSOLUBLE  ASH. 

Incinerate  slowly  the  residue  from  the  extraction  of  water-soluble  material,  ob- 
taine  I  in  6  or  7,  until  all  the  carbon  is  burned  off,  cool  in  a  desiccator  containing 
sulphuric  acid  and  weigh. 

5  FATS. 

Place,  without  packing,  15  grams  of  the  leather,  as  prepared  under  1 ,  in  a  Soxhlet 
or  Johnson  extractor  with  a  layer  of  fat-free  cotton  above  and  below  the  sample. 
Extract  8-10  hours  with  petroleum  ether  distilling  between  50°  and  80°C.  Heavily 
greased  leathers  (containing  15%  or  more  fat)  will  require  the  maximum  time.  Re- 
move the  receiving  flask,  evaporate  the  petroleum  ether  on  the  stc  am  bath  and  dry 
the  fat  residue  for  3  hours  in  a  water  oven  at  98°-100°C.,  cool  in  a  desiccator  and 
weigh.  Repeat  the  drying  in  the  water  oven  for  periods  of  l-U  hours,  cooling  and 
weighing  as  before,  until  no  further  loss  in  weight  occurs.  Retain  the  leather 
residue  from  the  fat  extraction  for  the  extraction  of  water-soluble  material  in  6  or  7. 

EXTRACTION  OF  WATER-SOLUBLE  MATERIAL. 

6  Method  I. 

Evaporate  the  petroleum  ether  from  the  fat-free  leather,  obtained  under  5,  and 
moisten  thoroughly  with  from  100-150  cc.  of  water.    Place  a  layer  of  cotton  in  the 

59 


60  METHODS    OF   ANALYSIS  [Chap. 

bottom  of  a  Soxhlet  extractor  designed  for  making  extractions  at  temperatures  be- 
low 100°C. 

An  extractor  of  this  kind  is  furnished  with  a  water  jacket  surrounding  that  por- 
tion of  the  apparatus  containing  the  sample  but  does  not  enclose  the  side  tube  which 
carries  the  hot  vapors  to  the  condenser. 

Transfer  the  moistened  fat-free  leather  to  the  extractor,  and  cover  this  with 
another  layer  of  cotton  to  avoid  siphoning  off  solid  particles.  Maintain  the  tempera- 
ture of  the  jacket  surrounding  the  Soxhlet  at  50°C.  (1)  Pour  200  cc.  of  water  (in- 
cluding that  used  in  moistening  the  leather)  into  the  Soxhlet  and  allow  it  to  siphon 
into  the  flask  below,  then  heat  and  extract  for  an  hour.  Remove  the  flame  and  trans- 
fer the  extract  to  a  liter  graduated  flask.  Then  add  water  and  continue  the  ex- 
traction as  directed  below,  removing  and  transferring  the  extract  to  the  liter 
flask  before  each  fresh  addition  of  water. 

(2)  Add  175  cc.  of  water  and  extract  for  2  hours. 

(3)  Add  175  cc.  of  water  and  extract  for  3  hours. 

(4)  Add  175  cc.  of  water  and  extract  for  4  hours. 

(5)  Add  175  cc.  of  water  and  extract  for  4  hours. 

Transfer  the  last  portion  of  the  extract  to  the  graduated  flask.  This  gives  14 
hours'  extraction  and  an  extract  which  does  not  exceed  1  liter  in  volume.  Dilute  to  1 
liter  at  room  temperature  and  mix  thoroughly. 

7  Method  11. 

(This  method  is  the  same  in  principle  as  the  official  method  of  the  American  Leather 
Chemists  Association. i) 

Digest  overnight  30  grams  of  the  fat-free  leather,  obtained  under  5,  in  approxi- 
mately 200  cc.  of  water.  Transfer  the  leather  and  extract  to  a  percolator.  Continue 
the  extraction  by  percolating  with  water  at  50°C.  Collect  2  liters  of  percolate, 
regulating  the  flow  of  water  at  such  a  rate  that  2  liters  will  be  collected  in  3  hours. 
Dilute  to  volume  at  room  temperature  and  mix  thoroughly. 

To  the  extract,  prepared  according  to  6  or  7,  add  a  few  drops  of  toluol  to  prevent 
fermentation  of  sugars,  and  reserve  for  the  determination  of  glucose,  total  solids, 
soluble  solids,  and  nontannins. 


O  PREPARATION   OP   SOLUTION. 

To  200  cc.  of  the  leather  extract,  as  prepared  under  6  or  7,  add  25  cc.  of  a  saturated 
solution  of  normal  lead  acetate,  mix  thoroughly,  and  filter  at  once  through  a  dry, 
plaited  paper,  returning  the  first  portions  of  the  filtrate  to  the  filter  until  the  fil- 
trate becomes  clear.  Keep  the  containers  and  the  funnel  covered  during  these  opera- 
tions. Without  waiting  for  the  entire  filtrate  to  run  through  add  10-12  grams 
of  solid  potassium  oxalate,  shake  frequently  during  15-20  minutes  and  filter  through 
a  dry,  plaited  paper  returning  the  "first  runnings  to  the  filter  until  the  filtrate  runs 
clear.  Pipette  150  cc.  of  the  last  filtrate  into  a  600  cc.  Erlenmeyer  flask,  add  5  cc.  of 
concentrated  hydrochloric  acid  and  boil  under  a  reflux  condenser  for  2  hours.  Cool, 
neutralize  with  solid  sodium  carbonate,  using  a  little  phenolphthalein  as  indicator, 
transfer  to  a  200  cc.  volumetric  flask  and  complete  to  volume  with  water.  Filter 
through  a  double  filter,  and  return  the  first  runnings  until  the  filtrate  becomes 
perfectly  clear.     Determine  the  dextrose  in  the  filtrate  immediately. 


VI]  LEATHERS  61 

9  DETEKMINATION. 

Determine  dextrose  in  50  cc.  of  the  solution,  as  prepared  under  8,  equivalent  to 
0.5  gram  of  leather,  according  to  VIII,  25  and  express  the  result  as  glucose. 

I  0  TOTAL  SOLIDS. 

Determine  as  directed  under  V,  2. 

I I  SOLUBLE  SOLIDS. 

Determine  as  directed  under  V,  4. 
1 2  NONTANNINS. 

Determine  as  directed  under  V,  7. 

1  3  SOLUBLE  TANNIN. 

The  difference  between  the  percentage  of  the  soluble  solids  and  the  corrected 
nontannins  is  the  percentage  of  tannin. 

1 4  NITROGEN. 

Determine  as  directed  under  I,  21 . 
1  5  HIDE  SUBSTANCE. 

Multiply  the  percentage  of  nitrogen  by  5.62.  The  result  will  be  the  percentage 
of  hide  substance  present. 

16  COMBINED  TANNIN. 

Deduct  the  sum  of  the  percentages  of  moisture,  under  2,  insoluble  ash,  under  4, 
soluble  solids,  under  1 1 ,  and  hide  substance,  under  1 5,  from  100.  The  result  will 
be  the  percentage  of  combined  tannin. 

BIBLIOGRAPHY. 
»  J.  Am.  Leather  Chem.  Assn.,  1915,  10:  122. 


VII.     INSECTICIDES  AND  FUNGICIDES. 
GENERAL  METHOD. 

1  PREPARATION  OF  SAMPLE.— TENTATIVE. 

Mix  thoroughly  all  samples  before  analysis.  Make  water-soluble  arsenic  deter- 
minations on  samples  as  received  without  further  pulverization  or  drying.  In 
the  case  of  lye,  sodium  cyanid  or  potassium  cyanid,  weigh  large  quantities  in  weigh- 
ing bottles  and  analyze  aliquots  of  the  aqueous  solutions. 

PARIS  GREEN. 

2  MOISTURE.— TENTATIVE. 

Dry  2  grams  at  105°-110°C.  for  5  hours  and  express  the  loss  in  weight  as  moisture. 

TOTAL  ARSENIC.!— OFFICIAL. 

(Arsenic,  present  as  arsenate,  is  titrated  as  arsenious  oxid.) 

3  REAGENTS. 

(a)  Starch  indicator . — Mix  about  0.5  gram  of  finely  powdered  potato  starch  with 
cold  water  to  a  thin  paste;  pour  into  about  100  cc.  of  boiling  water. 

(b)  Standard  arsenious  oxid  solution. — Dissolve  2  grams  of  pure  arsenious  oxid 
in  a  beaker  by  boiling  with  about  150-200  cc.  of  water  containing  10  cc.  of  concen- 
trated sulphuric  acid,  cool,  transfer  to  a  500  cc.  graduated  flask  and  dilute  to  the 
mark. 

(C)  Standard  iodin  solution. — Prepare  an  approximately  N/20  solution  as  fol- 
lows: Mix  intimately  6.35  grams  of  pure  iodin  with  twice  its  weight  of  pure  potas- 
sium iodid.    Dissolve  in  a  small  amount  of  water,  filter  and  dilute  the  filtrate  to 

1  liter  in  a  liter  graduated  flask.  Standardize  against  (b)  as  follows:  Pipette  50 
cc.  of  the  arsenious  oxid  into  an  Erlenmeyer  flask,  dilute  to  about  400  cc,  neutralize 
with  sodium  bicarbonate,  add  4-5  grams  in  excess,  and  add  the  standard  iodin  solu- 
tion from  a  burette,  shaking  the  flask  continuously,  until  the  yellow  color  disap- 
pears slowly  from  the  solution,  then  add  5  cc.  of  the  starch  indicator  and  continue 
adding  the  iodin  solution,  drop  by  drop,  until  a  permanent  blue  color  is  obtained. 
Calculate  the  value  of  the  standard  iodin  solution  in  terms  of  arsenious  oxid  \As2Os) 
and  arsenic  oxid  (AS2O5).  Occasionally  restandardize  the  iodin  against  freshly 
prepared  arsenious  oxid  solution. 

4  APPARATUS. 

The  apparatus  used  is  shown  in  Fig.  5.  The  distillation  flask  rests  on  a  metal 
gauze  which  fits  over  a  circular  hole  in  a  heavy  sheet  of  asbestos  board.     The  first 

2  Erlenmeyer  flasks  are  of  500  and  1000  cc.  capacity  and  contain  about  40  and  100 
cc.  of  water,  respectively.  Both  of  these  flasks  should  be  placed  in  a  pan  and  kept 
surrounded  with  cracked  ice  and  water.  The  third  flask,  containing  a  small  amount 
of  water,  is  used  as  a  trap. 


64 


METHODS    OF   ANALYSIS 


[Chap. 


3  DETERMINATION. 

Weigh  an  amount  of  the  sample  equal  to  the  arsenious  oxid  equivalent  of  250 
cc.  of  the  standard  iodin  solution,  and  wash  into  the  distillation  flask  by  means  of 
100  cc.  of  concentrated  hydrochloric  acid  (sp.  gr.  1.19).  Add  5  grams  of  cuprous 
chlorid    (Cu2Cl2)   and  distil. 

When  the  volume  in  the  distillation  flask  is  reduced  to  about  40  cc,  add  50  cc. 
of  concentrated  hydrochloric  acid  by  means  of  the  dropping  funnel  and  continue 
the  distillation  until  200  cc.  of  the  acid  distillate  have  passed  over.  Then  wash 
down  the  condenser  and  all  the  connecting  tubes  carefully,  transfer  these  washings 
and  the  contents  of  the  3  Erlenmeyer  flasks  to  a  liter  graduated  flask  and  dilute 
to  the  mark.  Mix  thoroughly,  pipette  400  cc.  into  an  Erlenmeyer  flask  and  nearly 
neutralize  with  a  saturated  solution  of  sodium  or  potassium  hydroxid,  using  a  few 
drops  of  phenolphthalein  as  an  indicator,  keeping  the  solution  well  cooled. 

Continue  as  directed  under  3  (C)  beginning  with  "neutralize  with  sodium  bicar- 
bonate." The  number  of  cc.  of  iodin  used  in  this  titration  represents  directly 
the  total  per  cent  of  arsenic  in  the  sample  expressed  as  arsenious  oxid  (AsjOa). 


FIG.  5.  APPARATUS  FOR  DISTILLATION  OF  ARSENIC  CHLORID. 

TOTAL  ARSENIOUS  OXID. 

(The  following  methods  determine  arsenic,  and  antimony  if  present,  as  the  -ous 
oxids,  AS2O3  and  Sb203,  respectively.    Ferrous  and  cuprous  salts  vitiate  the  results.) 


Method  I. 
C.  C.  Hedges  Method,^  Modified.^— Tentative. 

6  REAGENTS. 

The  reagents  and  solutions  used  are  described  under  3. 

7  DETERMINATION. 

Weigh  an  amount  of  the  sample  equal  to  the  arsenious  oxid  equivalent  of  100  cc. 
of  the  standard  iodin  solution,  wash  into  an  Erlenmeyer  flask  with  10-15  cc.  of  dilute 
hydrochloric  acid  (1  to  1),  followed  by  about  100  cc.  of  water,  and  heat  on  the  steam- 
bath  to  complete  solution,  at  a  temperature  not  exceeding  60°C.     Cool,  neutralize 


VII]  INSECTICIDES    AND   FUNGICIDES  65 

with  sodium  bicarbonate,  add  4-5  grams  in  excess,  and  then  sufficient  25%  ammonium 
chlorid  solution  to  dissolve  the  precipitated  copper.  Dilute  somewhat  and  titrate 
as  directed  under  3  (C) .  A  correction  must  be  applied  for  the  amount  of  iodin  solu- 
tion necessary  to  produce  a  blue  color  with  starch  in  the  presence  of  copper  (using 
an  equivalent  weight  of  copper  sulphate) .  The  corrected  number  of  cc .  of  the  stand- 
ard iodin  solution  used  represents  directly  the  per  cent  of  arsenious  oxid  (AsiOi) 
in  the  sample. 

Method  II. 

8  CM.  Smith  Method,^  Modified— Tentative. 

Proceed  as  directed  in  7,  using  dilute  sulphuric  acid  (1  to  4)  instead  of  dilute 
hydrochloric.    The  solution  in  this  case  may  be  heated  to  boiling. 

SODIUM  ACETATE-SOLUBLE  ARSENIOUS  OXID.<— TENTATIVE. 

9  REAGENTS. 

(a)  Sodium  acetate  solution .—Vrepare  a  solution  containing  12.5  grams  of  the 
crystallized  salt  (CHaCOONaSHzO)  in  each  25  cc. 
The  other  reagents  are  described  under  3. 

10  DETERMINATION. 

Place  1  gram  of  the  sample  in  a  100  cc.  flask  and  boil  for  5  minutes  with  25  cc.  of 
the  sodium  acetate.  Dilute  to  the  mark,  shake,  and  pass  through  a  dry  filter 
paper.  Titrate  an  aliquot  of  this  filtrate  as  directed  under  3  (C).  Calculate  the 
amount  of  arsenious  oxid  (AS2O3)  present  and  express  the  result  as  per  cent  of 
sodium  acetate-soluble  arsenious  oxid. 

WATER-SOLUBLE  ARSENIOUS  OXID.— TENTATIVE. 

11  REAGENTS. 

Described  under  3. 

12  DETERMINATION. 

To  1  gram  of  the  sample  in  a  liter  Florence  flask  add  1  liter  of  recently  boiled  water 
which  has  been  cooled  to  exactly  32°C.  Stopper  the  flask  and  place  in  a  water 
bath  kept  at  32°C.  by  means  of  a  thermostat.  Digest  for  24  hours,  shaking  hourly 
for  8  hours  during  this  period.  Filter  through  a  dry  filter  and  titrate  250  cc.  of  the 
filtrate  as  directed  under  3  (C) .  Correct  for  the  amount  of  the  standard  iodin  neces- 
sary to  produce  the  same  color,  using  the  same  reagents  and  volume.  Calculate 
the  amount  of  arsenious  oxid  (AS2O3)  present  and  express  the  result  as  per  cent  of 
water-soluble  arsenious  oxid. 

TOTAL  COPPER  OXID. 

13  Electrolytic  Method.— Official. 

Treat  2  grams  of  the  sample  in  a  beaker  with  100  cc.  of  water  and  about  2  grams 
of  sodium  hydroxid  and  boil  thoroughly  until  all  the  copper  is  precipitated  as  cu- 
prous oxid.  Filter,  wash  well  with  hot  water,  dissolve  the  precipitate  in  hot  dilute 
nitric  acid,  cool,  transfer  to  a  250  cc. graduated  flask  and  dilute  to  the  mark.  (1) 
Use  50-100  cc.  of  this  solution  for  the  electrolytic  determination  of  copper  as  directed 
under  VIII,  33  and  calculate  to  per  cent  cupric  oxid;  or,  (2)  Electrolyze  the  aliquot  in 
a  weighed  150  cc.  platinum  dish,  using  a  rotating  spiral  anode  and  a  current  of  about 


66  METHODS    OF   ANALYSIS  [Chap. 

3  amperes.  After  all  the  copper  is  deposited  (requiring  about  30  minutes),  wash 
the  deposit  with  water  bj^  siphoning,  then  rinse  with  alcohol,  dry  for  a  few  min- 
utes in  an  oven,  weigh  and  calcula.e  to  per  cent  cupric  oxid. 

14  Thiosulphate  Method.^— Official. 

Determine  copper  in  another  aliquot  of  the  nitric  acid  solution  of  copper  oxid, 
under  13,  by  titrating  with  N/20  thiosulphate  solution,  as  directed  under  VIII,  29, 
and  calculate  to  per  cent  cupric  oxiJ. 

LONDON  PURPLE. 

15  MOISTURE.-TENTATIVE. 
Determined  as  directed  under  2. 

TOTAL  ARSENIOUS  OXID.«— OFFICIAL. 

16  REAGENTS. 

Described  under  3. 

17  DETERMINATION. 

Dissolve  2  grams  of  the  sample  in  a  mixture  of  about  80  cc.  of  water  and  20  cc. 
of  concentrated  hydrochloric  acid  at  a  temperature  of  60°-70°C.;  filter  and  wash 
until  the  combined  filtrate  and  washings  measure  250  cc.  Treat  100  cc.  of  this  solu- 
tion with  sodium  bicarbonate  in  excess,  transfer  to  a  500  cc.  volumetric  flask  and 
make  up  to  the  mark,  adding  a  few  drops  of  ether  to  destroy  the  bubbles.  Mix 
thoroughly  and  pass  through  a  dry  filter.  Titrate  250  cc.  of  the  filtrate  as  directed 
under  3  (C)  and  calculate  the  per  cent  of  arsenious  oxid. 

TOTAL  ARSENIC  OXID.'— OFFICIAL. 

18  REAGENTS. 

The  reagents  and  solutions  used  are  described  under  3. 

19  DETERMINATION. 

Boil,  on  a  hot  plate  or  over  a  low  flame,  2  grams  of  the  sample  with  5  cc.  of  con- 
centrated nitric  acid  and  20  cc.  of  concentrated  sulphuric  acid  in  a  Kjeldahl  diges- 
tion flask  or  a  covered  casserole.  After  10-15  minutes  add  fuming  nitric  acid  or 
powdered  sodium  nitrate,  in  small  quantities  at  a  time,  until  all  organic  matter 
is  destroyed  and  the  solution  is  practically  colorless.  Cool,  add  about  50  cc.  of 
water  ito  decompose  any  nitro-sulphuric  acid  formed)  and  heat  again  until  all 
nitric  acid  fumes  are  expelled.  Cool,  transfer  to  a  250  cc.  volumetric  flask,  make 
up  to  the  mark  with  water,  mix  thoroughly,  and  filter  through  a  dry  filter. 

Transfer  50  cc.  of  this  filtrate  to  a  400  cc.  Erlenmeyer  flask,  dilute  with  water 
to  100  cc,  add  1  gram  of  potassium  iodid,'  heat  to  boiling  and  evaporate  to  about 
40  cc.  not  less).  Cool,  dilute  to  150-200  cc,  and  remove  the  excess  of  iodin  with 
N/20  sodium  thiosulphate.  In  case  the  solution  is  slightly  colored  from  organic 
matter  or  from  any  cause  other  than  free  iodin,  add  the  thiosulphate  until  it  is  nearly 
colorless,  then  a  few  drops  of  the  starch  indicator,  and  continue  adding  the  thio- 
sulphate slowly  until  the  l)luo  color  just  disappears.  Continue  at  once  as  directed 
under  3  C)  beginning  with  "neutralize  with  sodium  bicarbonate."  Subtract  from 
this  reading  the  number  of  cc.  of  the  standard  iodin  solution  corresponding  to  the 
arsenious  oxid  obtained  in  1 7.    Calculate  the  per  cent  of  arsenic  oxid  in  the  sample. 


VII]  INSECTICIDES   AND    FUNGICIDES  67 

20  WATER-SOLUBLE  ARSENIOUS  OXID.— TENTATIVE. 

Proceed  as  directed  under  12,  slightly  acidifying  the  aliquot  employed  with 
hydrochloric  acid  before  adding  the  excess  of  sodium  bicarbonate. 

WATER-SOLUBLE  ARSENIC  OXID.-TENTATIVE. 

21  REAGENTS. 

The  solutions  and  reagents  used  are  described  under    3. 

22  DETERMINATION. 

Transfer  an  aliquot,  250  cc,  of  the  water  extract,  from  20,  to  a  casserole,  add  5 
cc.  of  concentrated  sulphuric  acid,  evaporate  to  a  small  volume  and  heat  on  a  hot 
plate  till  white  fumes  of  sulphuric  acid  appear.  Cover  the  casserole  and  add  1-2 
cc.  of  fuming  nitric  acid  and  again  heat  till  the  appearance  of  white  fumes.  Cool, 
add  a  little  water  and,  in  order  to  expel  the  last  traces  of  nitric  acid,  once  more 
evaporate  till  white  fumes  appear.  Cool,  dilute  to  about  100  cc.  with  water,  add 
1  gram  of  potassium  iodid^  and  sufficient  sulphuric  acid  to  make  the  total  amount 
present  about  5  cc.  Boil  until  the  vo'ume  is  reduced  to  about  40  cc.  Cool,  dilute 
to  about  200  cc,  remove  the  excess  iodin  with  N/20  sodium  thiosulphate  and  pro- 
ceed as  directed  under  3  (C)  beginning  with  "neutralize  with  sodium  bicarbonate." 
Correct  for  the  amount  of  the  standard  iodin  solution  necessary  to  produce  the 
same  color,  using  the  same  reagents  and  volume.  Subtract  from  the  corrected  titra- 
tion reading  the  number  of  cc.  of  the  standard  iodin  solution  corresponding  to  the 
arsenious  oxid,  obtained  in  20.     Calculate  the  per  cent  of  arsenic  oxid  present. 

LEAD  ARSENATE. 

23  MOISTURE.-TENTATIVE. 

(a)  Powder. — Dry  2  grams  to  constant  weight  at  lOS^-llO"  C.  and  report  the 
loss  in  weight  as  moisture. 

(b)  Paste. — Proceed  as  under  (a),  using  50  grams. 

Grind  the  dry  sample  to  a  fine  powder,  mix  well,  transfer  a  small  portion  to  a 
sample  bottle  and  again  dry  for  1-2  hours  at  105°-110°C.,  and  use  this  anhydrous 
material  for  the  determination  of  total  lead  oxid  and  total  arsenic. 

TOTAL  LEAD  OXID. 

24  Method  I. ^—Official. 

Heat,  on  a  hot  plate,  0.6906  gram  of  the  dry  powdered  sample  with  about  25  cc. 
of  dilute  nitric  acid  (1  to  4)  in  a  600  cc.  beaker.  If  necessarj^  remove  any  insoluble 
residue  by  filtration.  Dilute  to  at  least  400  cc,  heat  nearly  to  boiling,  add  am- 
monium hydroxid  to  incipient  precipitation,  then  dilute  nitric  acid  ,1  to  10)  to  re- 
dissolve  the  precipitate,  adding  1-2  cc.  in  excess.  Pipette  into  this  solution,  kept 
almost  boiling,  50  cc.  of  a  hot  10%  potassium  chromate  solution,  stirring  constantly. 
Decant  while  hot  through  a  weighed  Gooch,  previously  heated  at  140°-150°C.,  wash 
several  times  by  decantation  and  then  on  the  filter  with  boiling  water  until  the 
washings  are  colorless.  Dry  the  lead  chromate  at  UO'-LoO^C.  to  constant  weight. 
The  weight  of  lead  chromate  multiplied  by  100  gives  the  per  cent  of  lead  monoxid 
(PbO)  in  the  dried  sample. 

The  lead  chromate  precipitate  maj'  contain  a  small  amount  of  lead  arsenate  which 
causes  slightly  high  results.     This  error  rarely  amounts  to  more  than  0.1-0.2%. 


68  METHODS   OF   ANALYSIS  [Chap. 

Method  11. ^0— Tentative. 
(Not  applicable  in  the  presence  of  calcium.) 

25  REAGENT. 

Acidified  alcohol.— Mix  water  100  parts;  95%  alcohol  200  parts;  and  concentrated 
sulphuric  acid  3  parts  by  volume. 

26  DETERMINATION. 

Heat,  on  a  hot  plate,  0.73G0  gram  of  the  dry  powdered  sample  with  about  25  cc. 
of  dilute  nitric  acid  (1  to  4)  in  a  porcelain  evaporating  dish  or  casserole.  Remove 
any  insoluble  residue  by  filtration.  Add  3  cc.  of  concentrated  sulphuric  acid  and 
evaporate  on  the  hot  plate  to  the  appearance  of  white  fumes.  It  is  important  that 
all  nitric  acid  be  expelled.  Cool,  add  50  cc.  of  water  and  about  100  cc.  of  95%  alco- 
hol, let  stand  several  hours  (preferably  over-night)  and  filter  through  a  weighed 
Gooch  crucible,  previously  washed  with  water,  the  acidified  alcohol  and  95%  alco- 
hol, and  dried  at  200°C.  Wash  the  precipitate  of  lead  sulphate  in  the  crucible  about 
10  times  with  the  acidified  alcohol  and  then  with  95%  alcohol  until  free  from  sul- 
phuric acid.  Dry  at  200°C.  to  constant  weight,  keeping  the  crucible  covered  to  pre- 
vent loss  by  spattering.  The  weight  of  the  lead  sulphate  multiplied  by  100  gives 
the  per  cent  of  lead  monoxid  (PbO)  in  the  dried  sample. 
TOTAL  ARSENIC. 

27  Method  I. ^—Official. 

Proceed  as  directed  under  5,  using  an  amount  of  the  sample  equal  to  the  arsenic 
oxid  equivalent  of  500  cc .  of  the  standard  iodin  solution  and  titrating  a  200  cc .  aliquot 
of  the  distillate.  The  number  of  cc.  used  of  the  standard  iodin  solution  represents 
directly  the  total  per  cent  of  arsenic  in  the  sample  expressed  as  arsenic  oxid  (AS2O6) . 

Method  11.^^— Official. 
(Not  applicable  in  the  presence  of  antimony.) 

28  REAGENTS. 

The  reagents  and  solutions  used  are  described  under  3. 

29  DETERMINATION. 

Dissolve  an  amount  of  the  powdered  sample  equal  to  the  arsenic  oxid  equivalent 
of  400  cc.  of  the  standard  iodin  solution,  in  dilute  nitric  acid  in  a  porcelain  casserole 
or  evaporating  dish.  Add  5  cc.  of  concentrated  sulphuric  acid  and  heat  on  the 
hot  plate  to  copious  evolution  of  white  fumes.  Wash  into  a  200  cc.  graduated  flask 
with  water,  cool,  make  up  to  the  mark  and  filter  through  a  dry  filter.  Transfer 
100  cc.  of  the  filtrate  to  an  Erlenmeyer  flask  and  proceed  as  directed  under  22, 
beginning  with  ''add  1  gram  of  potassium  iodid,"  to  "Subtract  from  the  corrected 
titration  reading."  The  number  of  cc.  of  the  standard  iodin  solution  used,  divided 
by  2,  represents  directly  the  per  cent  of  total  arsenic  in  the  sample  expressed  as 
arsenic  oxid  (As205)- 

WATER-SOLUBLE  ARSENIC  OXID. -TENTATIVE. 

30  REAGENTS. 

The  reagents  and  solutions  used  are  described  under  3. 


Vn]  INSECTICIDES   AND    FUNGICIDES  69 

31  DETERMINATION. 

Treat  2  grams  of  the  original  sample,  if  in  the  form  of  a  powder,  or  4  grams,  if 
a  paste,  as  directed  under  12  through  "Filter  through  a  dry  filter." 

Place  250-500  cc.  of  the  clear  filtrate  in  an  Erlenmeyer  flask,  add  3  cc.  of  con- 
centrated sulphuric  acid  and  evaporate  on  a  hot  plate.  When  the  volume  is  re- 
duced to  about  100  cc,  proceed  as  directed  under  22  to  "Subtract  from  the  cor- 
rected titration  reading."  Calculate  and  report  as  per  cent  of  water-soluble  arsenic 
oxid  (AsiOs). 

CALCIUM  ARSENATE. 

32  TOTAL  ARSENIC— OFFICIAL. 

Proceed  as  directed  under  5,  using  an  amount  of  the  powdered  sample  equal 
to  the  arsenic  oxid  equivalent  of  250  cc.  of  the  standard  iodin  solution. 

The  number  of  cc.  of  the  standard  iodin  solution  used  represents  directly  the 
total  per  cent  of  arsenic  in  the  sample  expressed  as  arsenic  oxid  (AS2O8) . 

ZINC  ARSENITE. 

33  TOTAL  ARSENIC.1-0FFICLA.L. 

Proceed  as  directed  under  5,  using  an  amount  of  the  powdered  sample  equal  to 
the  arsenious  oxid  equivalent  of  500  cc.  of  the  standard  iodin  solution  and  titrating 
a  200  cc.  aliquot  of  the  distillate.  The  number  of  cc.  of  the  standard  iodin  solution 
used  represents  directly  the  per  cent  of  total  arsenic  in  the  sample  expressed  as  ar- 
senious oxid  (AS2O3). 

34  TOTAL  ARSENIOUS  OXID.— TENTATIVE. 
Proceed  as  directed  under  7  or  8. 

COPPER  CARBONATE. 

35  COPPER  OXID.— OFFICIAL. 

Dissolve  a  weighed  quantity  of  the  substance  in  dilute  nitric  acid  and  deter- 
mine copper  as  directed  under  13  or  14. 

BORDEAUX  MIXTURE. 

36  MOISTURE.-OFFICIAL. 

(a)  Powder. — Dry  2  grams  to  constant  weight  at  105°-110°C.  and  express  the 
loss  in  weight  as  moisture. 

(b)  Paste. — Heat  about  100  grams  in  an  oven  at  90-100°C.  until  dry  enough  to 
powder  readily,  and  note  the  loss  in  weight.  Powder  this  partially  dried  sample, 
and  determine  the  remaining  moisture  in  2  grams  as  under  la).  Determine  car- 
bon dioxid,  as  directed  under  38,  both  in  the  original  paste  and  in  this  partially 
dried  sample.    Calculate  the  total  moisture  by  the  following  formula: 

M  =  a  +  (100-a)  (b  +  c)  -  d  in  which 

M  =  per  cent  total  moisture  in  original  paste; 

a    =  per  cent  loss  in  weight  of  original  paste  during  first  drying; 

b    =  per  cent  loss  in  weight  of  partially  dried  paste  during  second  drying; 

c     =  per  cent  carbon  dioxid  remaining  in  partially  dried  paste  after  first 

drying; 
d    =  per  cent  total  carbon  dioxid  in  original  paste. 


70  METHODS    OF   ANALYSIS  [Chap. 

CARBON  DIOXID."— OFFICIAL. 

37  APPARATUS. 

This  consists  of  a  200  cc.  Erlenmeyer  flask  closed  with  a 2-holed  stopper;  one  of 
these  holes  is  fitted  with  a  dropping  funnel  the  stem  of  which  extends  almost  to  the 
bottom  of  the  flask;  the  outlet  of  a  condenser,  which  is  inclined  upward  at  an  angle 
of  30°  from  the  horizontal,  passes  downward  through  the  other  hole.  The  upper 
end  of  the  condenser  is  connected  with  a  calcium  chlorid  tube  which  in  turn  ia 
connected  with  a  double  U-tube  filled  in  the  middle  with  pumice  fragments,  pre- 
viously saturated  with  copper  sulphate  solution  and  subsequently  dehydrated, 
and  with  calcium  chlorid  at  either  end.  Then  follow  2  weighed  U-tubes  for  absorb- 
ing the  carbon  dioxid,  the  first  filled  with  porous  soda-lime,  and  the  second,  one 
third  with  soda-lime  and  two  thirds  with  calcium  chlorid,  the  latter  reagent  being 
placed  at  the  exit  end  of  the  train.  A  Geissler  bulb,  partly  filled  with  sulphuric 
acid,  is  attached  to  the  last  U-tube  to  show  the  rate  of  gas  flow.  An  aspirator  is 
connected  with  the  Geissler  bulb  to  draw  air  through  the  apparatus.  An  absorp- 
tion tower  filled  with  soda-lime  is  connected  with  the  mouth  of  the  dropping  funnel 
to  remove  carbon  dioxid  from  the  air  entering  the  apparatus. 

38  DETERMINATION. 

Weigh  2  grams  of  the  powder  or  10  grams  of  the  paste  into  the  Erlenmeyer  flask, 
add  about  20  cc.  of  water,  attach  the  flask  to  the  apparatus  omitting  the  2  weighed 
U-tubes,  and  draw  carbon  dioxid-free  air  through  the  apparatus  until  the  original 
air  is  displaced.  Then  attach  the  weighed  U-tubes  in  the  position  as  described  in  37, 
close  the  stop-cock  of  the  dropping  funnel,  fill  half  full  with  dilute  hydrochloric 
acid  (1  to  1),  reconnect  with  the  soda-lime  tower,  and  allow  the  acid  to  flow  into 
the  Erlenmeyer  flask,  slowly  if  there  is  much  carbon  dioxid,  rapidly  if  there  is 
little.  When  effervescence  diminishes,  place  a  low  Bunsen  flame  under  the  flask  and 
start  a  flow  of  water  through  the  condenser,  a  slow  current  of  air  being  allowed  to 
flow  through  the  apparatus  at  the  same  time.  Maintain  a  steady  but  quiet  ebulli- 
tion, and  a  slow  air  current  through  the  apparatus.  Boil  for  a  few  minutes  after 
the  water  has  begun  to  condense  in  the  condenser,  then  remove  the  flame  and  con- 
tinue the  aspiration  of  air  at  the  rate  of  about  2  bubbles  per  second  until  the 
apparatus  is  cool.  Disconnect  the  tared  absorption  tubes,  cool  in  the  balance  case 
and  weigh.    The  increase  in  weight  is  due  to  carbon  dioxid. 

COPPER. 

39  Electrolytic  Method.— Official. 

Dissolve  2  grams  of  the  dry  powdered  sample  in  20  cc.  of  water  and  5  cc.  of  con- 
centrated nitric  acid,  dilute  to  100  cc,  wash  into  a  weighed  150  cc.  platinum  dish, 
and  electrolyze,  using  a  rotating  spiral  anode  and  a  current  of  about  3  amperes. 
After  all  the  copper  is  deposited  (.requiring  about  30  minutes),  wash  the  deposit 
with  water  by  siphoning,  then  rinse  with  alcohol,  dry  for  a  few  minutes  in  an  oven, 
and  weigh.    Calculate  the  per  cent  of  copper  in  the  sample. 

40  Thiosulphate  Method.— Official. 

Dissolve  2  grams  of  the  dry  powdered  sample  in  about  50  cc.  of  10%  nitric  acid, 
add  ammonium  hydroxid  solution  in  excess  and  heat;  then,  without  removing  the 
precipitate  which  is  formed,  boil  off  the  excess  of  ammonia,  add  5-10  cc.  of  acetic 
acid,  cool,  add  10  cc.  of  30%  potassium  iodid  solution,  and  titrate  as  directed  under 
VIIL  29. 


Vn]  INSECTICIDES    AND    FUNGICIDES  71 

BORDEAUX  MIXTURE  WITH  PARIS  GREEN. 

41  MOISTURE.-OFFICIAL. 

Proceed  as  directed  under  36. 

42  CARBON  DIOXID.-OFnCIAL. 
Proceed  as  directed  under  38. 

COPPER. 

43  Method  I— Tentative. 

Dissolve  2  grams  of  the  dry  powdered  sample  in  a  few  cc.  of  strong  nitric  acid, 
add  25  cc.  of  a  3%  solution  of  hydrogen  peroxid  and  warm  for  5-10  minutes.  Make 
slightly  alkaline  with  ammonium  hydroxid  and  then  slightly  acid  again  with  dilute 
nitric  acid.  Transfer  to  a  weighed  150  cc.  platinum  dish,  add  15-20  cc.  of  hydrogen 
peroxid,  dilute  to  100  cc.  and  electrolyze,  using  a  rotating  spiral  anode  and  a  cur- 
rent not  exceeding  2  amperes.  After  the  electrolysis  has  proceeded  for  about  20 
minutes,  add  to  the  electrolyte  0.5  gram  of  ferric  sulphate  dissolved  in  a  few  cc. 
of  water  together  with  a  drop  or  two  of  nitric  acid.  After  all  the  copper  is  deposited, 
wash  the  deposit  with  water  by  siphoning,  then  rinse  with  alcohol,  dry  for  a  few 
minutes  in  an  oven,  weigh  and  calculate  the  per  cent  of  copper.  (Do  not  pass  the 
current  for  more  than  5-10  minutes  after  all  the  copper  has  been  deposited  without 
adding  more  ferric  sulphate  solution.) 

44  Method  II. — Tentative. 

Treat  1  gram  of  the  dry  powdered  sample  with  20  cc.  of  water  and  5-6  cc.  of  con- 
centrated nitric  acid,  heat  to  boiling,  cool,  and  add  a  slight  excess  of  concentrated 
ammonium  hydroxid.  Wash  the  solution  and  precipitate  into  a  weighed  platinum 
dish  of  about  150  cc.  capacity,  and  electrolyze,  using  a  rotating  anode  and  a  cur- 
rent of  about  4  amperes  and  3-4  volts  for  about  90  minutes  (.or  until  all  the  copper 
is  deposited) .  Wash  the  deposit  by  siphoning  until  the  deposit  is  clean,  being  care- 
ful not  to  use  too  much  wash  water.  Dissolve  the  copper  in  5  cc.  of  concentrated 
nitric  acid,  dilute  to  100  cc.  and  electrolyze  as  before,  except  that  all  the  copper 
will  be  deposited  in  30  minutes.  Wash  the  deposit  with  water  by  siphoning,  then 
rinse  with  alcohol,  dry  for  a  minute  or  so  in  an  oven,  weigh  and  calculate  the  per 
cent  of  copper. 

45  TOTAL  ARSENIC-OFFICIAL. 

Proceed  as  directed  under  5,  using  an  amount  of  the  dry  powdered  sample  equal 
to  the  arsenious  oxid  equivalent  of  500  cc.  of  the  standard  iodin  solution.  The  num- 
ber of  cc.  of  the  standard  iodin  solution  used,  divided  by  2,  represents  directly  the 
per  cent  of  total  arsenic  in  the  sample  expressed  as  arsenious  oxid  (AsjOs). 

TOTAL  ARSENIOUS  OXID. 

46  Method  I.— Tentative. 

Proceed  as  directed  under  7,  using  an  amount  of  the  dry,  powdered  sample  equal 
to  the  arsenious  oxid  equivalent  of  200  cc.  of  the  standard  iodin  solution.  Before 
titrating,  all  the  copper  must  be  in  solution.  The  corrected  number  of  cc.  of  the 
standard  iodin  solution  used,  divided  by  2,  represents  directly  the  per  cent  of  total 
arsenious  oxid  (AS2O3)  in  the  sample. 


72  METHODS    OF   ANALYSIS  [Chap. 

47  Method  II.— Tentative. 
Proceed  as  directed  under  8. 

48  WATER-SOLUBLE  ARSENIOUS  OXID.— TENTATIVE. 
Proceed  as  directed  under  20,  using  2  grams  of  the  sample. 

BORDEAUX  MIXTURE  WITH  LEAD  ARSENATE. 

49  MOISTURE.-OFFICLAL. 

Proceed  as  directed  under  36. 

50  CARBON  DIOXID.— OFFICIAL. 

Proceed  as  directed  under  38. 

51  COPPER.-TENTATIVE. 

Proceed  as  directed  under  44. 

52  LEAD  OXID.3— TENTATIVE. 

Dissolve  the  lead  peroxid  (which  will  contain  a  little  arsenic)  from  the  anodes 
used  in  the  copper  electrolysis,  under  51 ,  by  means  of  dilute  nitric  acid  and  a  little 
hydrogen  peroxid,  and  add  to  this  solution  the  washings  from  both  electrolyses 
of  copper.  Add  ammonium  chlorid  to  dissolve  any  lead  sulphate  which  may  have 
precipitated  out  and  make  the  solution  up  to  1  liter.  Concentrate  a  500  cc.  aliquot 
of  this  solution  to  about  300  cc.  (all  hydrogen  peroxid  must  be  expelled  from  the 
solution),  transfer  to  a  400  cc.  beaker  and  precipitate  the  lead  as  lead  chromate 
as  directed  under  24. 

53  TOTAL  ARSENIC.i-OFFICIAL. 

Proceed  as  directed  under  5,  using  an  amount  of  the  dry,  powdered  sample  equal 
to  the  arsenic  oxid  equivalent  of  500  cc.  of  the  standard  iodin  solution.  The  num- 
ber of  cc.  of  the  standard  iodin  solution  used,  divided  by  2,  represents  directly  the 
per  cent  of  total  arsenic  in  the  sample  expressed  as  arsenic  oxid  (AszOs). 

54  WATER-SOLUBLE  ARSENIC  OXID.-TENTATIVE. 
Proceed  as  directed  under  31 . 

SODIUM  AND  POTASSIUM  CYANIDS. 

55  CYANOGEN.is— OFFICLAL. 

Weigh  about  10  grams  of  the  sample  in  a  weighing  bottle,  dissolve  in  water,  and 
make  up  to  volume  in  a  liter  graduated  flask.  To  a  50  cc.  aliquot  add  N/20  silver 
nitrate,  drop  by  drop,  stirring  constantly,  until  1  drop  produces  a  permanent  tur- 
bidity. In  calculating  the  results,  1  equivalent  of  silver  is  equal  to  2  equivalents 
of  cyanogen,  according  to  the  following  equation: 

2NaCN  +  AgNOa  =  NaCNAgCN  +  NaNOj 

Reserve  the  titrated  solution  for  the  determination  of  chlorin  under  56. 


Vn]  INSECTICIDES    AND    FUNGICIDES  73 

5g  CHLORIN.K— OFFICIAL. 

After  completion  of  the  titration  for  cyanogen,  as  directed  under  55,  add  a  few 
cc.  of  10%  potassium  chromate  solution  as  indicator  and  titrate  with  N/20  silver 
nitrate  until  the  appearance  of  the  red-brown  color  of  silver  chromate. 

The  first  titration  with  silver  nitrate  represents  the  cyanogen  present  according 
to  the  equation  above.  The  second  titration  represents  the  cyanogen  and  chlorin 
according  to  the  following  equation :  NaCNAgCN  +  NaCl  +  2AgN03  =  2NaN03  + 
2AgCN  +  AgCl.  Therefore  the  second  minus  the  first  reading  represents  the  chlorin 
present  in  terms  of  silver  nitrate. 

SOAP. 


57  Modified  Method  of  Benedickt  and  Lewkowitsch.^^ — Tentative. 

Weigh  about  5  grams  of  the  sample  in  a  tared,  100  cc.  beaker,  in  which  is  pre- 
viously placed  a  5  inch  layer  of  recently  ignited,  dry  sand,  and  a  small  glass  rod; 
if  the  soap  is  hard,  cut  off  the  soap  in  very  thin  strips.  Add  25  cc.  of  alcohol, 
or  more  if  necessary,  and  dissolve  on  the  water  bath,  stirring  constantly.  Evapo- 
rate the  alcohol,  heat  in  an  oven  at  110°C.  until  the  soap  is  nearly  dry,  and  weigh, 
then  dry  again  for  30  minutes  and  weigh.  Continue  this  alternate  drying  and 
weighing  until  the  weight  changes  only  a  few  milligrams  during  the  course  of  30 
minutes'  drying. 

58  POTASSIUM  AND    SODIUM."— TENTATIVE. 

Dissolve  about  5  grams  of  the  soap  in  water;  decompose  with  hydrochloric  acid, 
filter  off  the  water  and  wash  the  fat  with  cold  water.  Determine  both  potassium 
and  sodium  in  the  filtrate  as  directed  under  II,  21 . 

SODA  LYE. 

59  CARBONATE  AND    HYDROXID.i'— OFFICIAL. 

Weigh  about  10  grams  of  the  sample  from  the  weighing  bottle,  dissolve  in  car- 
bon dioxid-free  water  and  make  up  to  a  definite  volume.  Titrate  an  aliquot  of  this 
solution  with  N/2  hydrochloric  acid,  using  methyl  orange  as  an  indicator,  and  note 
the  total  alkalinity  thus  found.  Transfer  an  equal  aliquot  to  a  graduated  flask 
and  add  enough  barium  chlorid  solution  to  precipitate  all  the  carbonate,  avoiding 
any  unnecessary  excess.  Dilute  to  the  mark  with  carbon  dio.xid-free  water,  stopper, 
shake,  and  set  aside.  When  the  liquid  becomes  clear,  pipette  off  one  half  and  ti- 
trate with  N/2  hydrochloric  acid,  using  phenolphthalein  as  an  indicator.  The 
number  of  cc.  of  N/2  acid,  required  for  this  titration,  multiplied  by  2  gives  the  num- 
ber of  cc.  of  N/2  acid  required  to  neutralize  the  sodium  hydroxid  present  in  the 
original  aliquot.  The  difference  between  this  figure  and  the  number  of  cc.  of  N/2 
hydrochloric  acid  required  for  the  total  akalinitj'  represents  the  number  of  cc.  of 
N/2  acid  required  to  neutralize  the  sodium  carbonate  present  in  the  aliquot.  Cal- 
culate the  percentages  of  sodium  carbonate  and  hydroxid  present  in  the  sample. 

TOBACCO  AND  TOBACCO  EXTRACT. 

NICOTIN. 

Kissling  Method. — Official. 

60  REAGENTS. 

(a)  Alcoholic  sodium  hydroxid  solution. — Dissolve  6  grams  of  sodium  hydroxid 
in  40  cc.  of  water  and  60  cc.  of  90%  alcohol. 


74  METHODS    OF   ANALYSIS  [Chap. 

(b)  04%  sodium  hydroxid  solution. 

(C)  N /W  sulphuric  acid. — One  cc.  is  equivalent  to  16.22  mg.  of  nicotin. 

(d)  Phenacetolin  solution. — Prepare  a  0.5%  alcoholic  solution. 

(e)  Cochineal  solution. — Prepare  as  directed  under  I,  16  (k). 

61  DETERMINATION. 

Weigh  5-6  grams  of  tobacco  extract,  or  20  grams  of  finely  powdered  tobacco 
which  has  been  previously  dried  at  60°C.  if  necessary,  into  a  small  beaker.  Add 
10  cc.  of  the  alcoholic  sodium  hydroxid  and  follow,  in  the  case  of  tobacco  extract, 
with  enough  pure  powdered  calcium  carbonate  to  form  a  moist  but  not  lumpy  mass. 
Mix  thoroughly,  transfer  to  a  Soxhlet  extractor  and  exhaust  for  about  5  hours  with 
ether.  Evaporate  the  ether  at  a  low  temperature,  and  take  up  the  residue  with  50 
cc.  of  the  0.4%  sodium  hydroxid  solution.  Transfer  this  residue  by  means  of  water 
to  a  500  cc.  Kjeldahl  flask,  and  distil  with  steam,  passing  the  distillate  through  a 
condenser  cooled  by  a  rapidly  flowing  current  of  water.  Use  a  3-bend  outflow  tube, 
and,  to  prevent  bumping  and  frothing,  add  a  few  pieces  of  pumice,  and  a  small  piece 
of  paraffin.  Distil  till  all  the  nicotin  has  passed  over,  the  distillate  usually  varying 
from  400-500  cc.  When  completed,  only  about  15  cc.  of  the  liquid  should  remain  in 
the  flask.  Titrate  the  distillate  with  N/10  sulphuric  acid,  using  the  phenacetolin 
or  cochineal  solution  as  indicator. 

Silicotungstic  Acid  Method.^^ — Official. 

62  REAGENTS. 

(a)  Silicotungstic  acid  solution. — Prepare  a  12%  solution  of  the  silicotungstic 
acid  having  the  following  formula:  4H20.Si02.12W03.22H20. 

(b)  Sodium  or  potassium  hydroxid  solution  [1  to  2). 
(C)  Dilute  hydrochloric  acid  {1  to  4)  • 

63  DETERMINATION. 

Weigh  such  an  amount  of  the  preparation  as  will  contain  preferably  between  0.1 
and  1.0  gram  of  nicotin  (if  the  sample  contains  very  little  nicotin,  about  0.1%,  do 
not  increase  the  amount  to  the  point  where  it  interferes  with  the  distillation) ;  wash 
with  water  into  a500cc.  round-bottomed  distillation  flask;  add  a  little  paraffin  to  pre- 
vent frothing,  a  few  small  pieces  of  pumice  and  a  slight  excess  of  the  sodium  or 
potassium  hydroxid,  using  phenolphthalein  as  an  indicator.  Distil  rapidly  in  a 
current  of  steam  through  a  well-cooled  condenser,  connected  by  means  of  an  adapter 
with  a  suitable  flask  containing  10  cc.  of  the  dilute  hydrochloric  acid.  When  distil- 
lation is  well  underway,  heat  the  distillation  flask  to  reduce  the  volume  of  the  liquid 
as  far  as  practicable  without  bumping  or  undue  separation  of  insoluble  matter.  Dis- 
til until  a  few  cc.  of  the  distillate  show  no  cloud  or  opalescence  when  treated  with  a 
drop  of  the  silicotungstic  acid  and  a  drop  of  the  dilute  hydrochloric  acid.  Confirm 
the  alkalinity  of  the  residue  in  the  distillation  flask  with  phenolphthalein  solution. 
Make  up  the  distillate,  which  may  amount  to  1000-1500  cc,  to  a  convenient  volume  (the 
solution  may  be  concentrated  on  the  steam  bath  without  loss  of  nicotin),  mix  well 
and  pass  through  a  large  dry  filter  if  not  clear.  Test  a  portion  with  methyl  orange 
to  assure  its  acidity.  Pipette  an  aliquot,  containing  about  0.1  gram  of  nicotin,  into 
a  beaker  lif  the  samples  contain  very  small  amounts  of  nicotin,  an  aliquot  contain- 
ing as  little  as  0.01  gram  of  nicotin  may  be  used),  add  to  each  100  cc.  of  liquid  3  cc. 
of  the  dilute  hydrochloric  acid,  or  more  if  the  necessity  is  indicated  by  the  test  with 
methyl  orange,  and  add  1  cc.  of  the  silicotungstic  acid  for  each  0.01  gram  of  nico- 


VII]  INSECTICIDES   AND    FUNGICIDES  75 

tin  supposed  to  be  present.  Stir  thoroughly  and  let  stand  overnight.  Before  filter- 
ing, stir  the  precipitate  to  see  that  it  settles  quickly  and  is  in  crystalline  form;  then 
filter  on  an  ashless  filter  paper,  and  wash  with  cold  dilute  hydrochloric  acid  (1  to 
1000).  Transfer  the  paper  and  precipitate  to  a  weighed  platinum  crucible,  dry 
carefully,  and  ignite  until  all  carbon  is  destroyed.  Finally  heat  over  a  Teclu  or 
Meker  burner  for  not  more  than  10  minutes.  The  weight  of  the  residue  multiplied 
by  0.114  gives  the  weight  of  nicotin  present  in  the  aliquot. 

FORMALDEHYDE  SOLUTIONS. 

FORMALDEHYDE. 

Hydrogen  Peroxid  Method.^^ — Official. 

64  REAGENTS. 

(a)  N/1  sulphuric  acid. 

(b)  N/1  sodium  hydroxid. — One  cc.  is  equivalent  to  30.02  mg.  of  formaldehyde. 
(C)  Hydrogen  peroxid. — An  approximately  3%  solution.     If  the  hydrogen  per- 
oxid solution  is  acid,  neutralize  with  (b),  using  litmus  solution  as  indicator. 

(d)  Litmus  solution. — A  solution  of  purified  litmus. 

65  DETERMINATION. 

Measure  50  cc.  of  N/1  sodium  hydroxid  into  a  500  cc.  Erlenmeyer  flask  and  add 
50  cc.  of  the  hydrogen  peroxid.  Then  add  3  grams  of  the  formaldehyde  solution  un- 
der examination,  allowing  the  point  of  the  pipette  to  reach  nearly  to  the  liquid  in  the 
flask.  Place  a  funnel  in  the  neck  of  the  flask  and  heat  on  the  steam  bath  for  5  min- 
utes, shaking  occasionally.  Remove  from  the  steam  bath,  wash  the  funnel  with 
water,  cool  the  flask  to  about  room  temperature,  and  titrate  with  N/1  acid,  using 
the  litmus  solution  as  indicator.  It  is  necessary  to  cool  the  flask  before  titration 
with  the  acid  to  get  a  sharp  end  point  with  the  litmus.  Calculate  the  per  cent  of 
formaldehyde. 

Cyanid  Method.^"— Official. 

66  REAGENTS. 

(a)  N^/IO  silver  nitrate. 

(b)  N/10  ammonium  sulphocyanate. 

(C)  Potassium  cyanid  solution. — Dissolve  3.1  grams  of  potassium  cyanid  in  500 
cc.  of  water. 

(d)  50%  nitric  acid. 

67  DETERMINATION. 

Treat  15  cc.  of  the  N/10  silver  nitrate  with  6  drops  of  the  50%  nitric  acid  in  a 
50  cc.  volumetric  flask;  add  10  cc.  of  the  potassium  cj-^anid  solution,  dilute  to  the 
mark,  shake  well,  filter  through  a  dry  filter  and  titrate  25  cc.  of  the  filtrate  with 
N/10  ammonium  sulphocyanate  as  directed  under  III,  15.  Acidify  another  15  cc. 
portion  of  the  N/10  silver  nitrate  with  6  drops  of  the  50%  nitric  acid  and  treat  with 
10  cc.  of  the  potassium  cyanid  solution  to  which  has  been  added  a  measured  quan- 
tity (the  weight  of  which  must  be  calculated  from  the  specific  gravity)  of  the  for- 
maldehyde solution  containing  not  over  2.5  grams  of  a  1%  solution  or  the  equiva- 
lent. Make  up  to  50  cc,  filter  and  titrate  a  25  cc.  aliquot  with  the  N/10  ammonium 
sulphocyanate  for  the  excess  of  silver  as  before.  The  difference  between  the  num- 
ber of  cc.  of  N/10  ammonium  sulphocyanate  used  in  these  2  titrations,  multiplied 


76  METHODS    OF   ANALYSIS  [Chap. 

by  2,  gives  the  number  of  cc.  of  N/10  ammonium  sulphocyanate  corresponding  to 
the  potassium  cyanic!  used  by  the  formaldehyde.  Calculate  the  per  cent  of  for- 
maldehyde present  U  cc.  of  N/10  ammonium  sulphocyanate  is  equivalent  to  3  mg.  of 
formaldehyde  (HCHO)). 

LIME-SULPHUR  SOLUTIONS.^i 

TOTAL  SULPHTJR.-OFFICIAL. 

68  PREPARATION   OF   SOLUTION. 

Weigh  10  grams  of  the  solution  and  dilute  to  the  mark  in  a  250  cc.  graduated 
flask  with  recently  boiled  and  cooled  water. 

69  DETERMINATION. 

Transfer  a  10  cc.  aliquot  to  a  400  cc.  beaker,  add  about  3  grams  of  sodium  peroxid, 
cover  immediately  with  a  watch  glass  and  warm  on  the  steam  bath,  with  frequent 
shaking,  until  all  the  sulphur  is  oxidized  to  sulphate,  adding  more  sodium  peroxid 
if  necessary.  Dilute,  acidify  with  hydrochloric  acid,  evaporate  to  dryness,  treat 
with  water  acidified  with  hydrochloric  acid,  boil,  and  filter  to  remove  silica,  if  pres- 
ent. Dilute  the  filtrate  to  300  cc,  add  50  cc.  of  concentrated  hydrochloric  acid," 
heat  to  boiling,  and  precipitate  with  10%  barium  chlorid  solution  slowly  and  stir- 
ring constantly.  (The  rate  is  best  regulated  by  attaching  a  suitable  capillary  tip 
to  the  burette  containing  the  barium  chlorid  solution.)  Evaporate  to  dryness  on 
the  steam  bath,  take  up  with  hot  water,  filter  through  a  quantitative  filter  paper, 
wash  until  free  from  chlorin,  ignite  and  heat  to  constant  weight  over  a  Bunsen 
burner.  Calculate  the  sulphur  from  the  weight  of  barium  sulphate.  Previous  to 
use  test  the  reagents  for  sulphur  and,  if  present,  make  corrections  accordingly. 

SULPHID  SULPHTJR.-OFFICIAL. 

70  REAGENT. 

Ammoniacal  zinc  solution. — Dissolve  50  grams  of  pure  zinc  chlorid  in  water,  add 
ammonium  hydroxid  in  sufficient  quantity  to  redissolve  the  precipitate  first  formed, 
then  add  50  grams  of  ammonium  chlorid^'  and  dilute  to  1  liter. 

71  DETERMINATION. 

Dilute  10  cc.  of  the  solution,  prepared  as  directed  under  68,  to  about  100  cc.  and 
add  the  ammoniacal  zinc  solution  until  the  sulphid  is  all  precipitated,  indicated  by 
the  addition  of  a  drop  of  the  clear  solution  to  a  few  drops  of  nickel  sulphate  solution. 
Filter  immediately,  wash  the  precipitate  thoroughly  with  cold  water  and  transfer 
it  and  the  filter  paper  to  a  beaker.  Cover  with  water,  disintegrate  with  a  glass  rod 
and  add  about  3  grams  of  sodium  peroxid,  keeping  the  beaker  well  covered  with  a 
watch  glass.  Warm  on  the  steam  bath  with  frequent  shaking  until  all  the  sulphur 
is  oxidized  to  sulphate,  adding  more  sodium  peroxid  if  necessary.  Make  slightly 
acid  with  hydrochloric  acid,  filter  to  remove  shreds  of  filter  paper,  wash  thoroughly 
with  hot  water,  and  determine  the -sulphur  in  the  filtrate  exactly  as  under  69. 

72  THIOSULPHATE  SULPHTJR.-OFFICIAL. 

Dilute  50  cc.  of  the  solution,  prepared  as  under  68,  to  about  100  cc.  in  a  200  cc. 
graduated  flask.  Add  a  slight  excess  of  the  ammoniacal  zinc  chlorid  and  dilute  to 
the  mark.  Shake  thoroughly  and  filter  through  a  dry  filter.  To  100  cc.  of  the  fil- 
trate add  a  few  drops  of  methyl  orange  and  exactly  neutralize  with  N/10  hydrochloric 


Vn]  INSECTICIDES   AND   FUNGICIDES  77 

acid.  Titrate  this  neutral  solution  with  approximately  N/20  iodin,  3  ^C),  using  a 
few  drops  of  starch  solution  as  indicator.  From  the  number  of  cc.  of  iodin  solu- 
tion used,  calculate  the  thiosulphate  sulphur  present. 

73  SULPHATE   SULPHUR.— OFFICIAL. 

To  the  solution  from  the  determination  in  72,  add  2  or  3  drops  of  hydrochloric 
acid,  precipitate  in  the  cold  with  10%  barium  chlorid  solution,  allow  to  stand  over- 
night, filter,  calculate  the  sulphur  from  the  weight  of  barium  sulphate  and  report 
as  sulphate  sulphur. 

74  TOTAL  LIME.— OFFICIAL. 

To  25  cc.  of  the  solution,  prepared  as  under  68,  add  10  cc.  of  concentrated  hydro- 
chloric acid,  evaporate  to  dryness  on  the  steam  bath,  treat  with  water  and  a  little 
hydrochloric  acid,  warm  until  all  the  calcium  chlorid  is  dissolved,  and  filter  from  sul- 
phur and  any  silica  that  may  be  present.  O.xidize  the  filtrate  by  boiling  with  a 
little  concentrated  nitric  acid,  make  ammoniacal,  filter  from  iron  and  aluminium 
if  present,  heat  to  boiling  and  precipitate  the  calcium  with  ammonium  oxalate  so- 
lution. Filter,  wash  and  ignite  over  a  blast  lamp  to  constant  weight;  weigh  the 
residue  as  calcium  o.xid. 

BIBLIOGRAPHY. 

1  J.  Ind.  Eng.  Chem.,  1916,  8:  327. 

'  Ibid.,  1909,  1:  208. 

»  J.  Assoc.  Official  Agr.  Chemists,  1915,  1:  436,  446. 

«  J.  Am.  Chem.  Soc,  1901,  23:  115. 

»  Ibid.,  1902,  24:  1082. 

«  Ibid.,  1900,  22:  802. 

'  U.  S.  Bur.  Chem.  Bull.  122,  p.  106. 

»  Am.  J.  Sci.,  1890.  3rd  ser.,  40:  66. 

'  U.  S.  Bur.  Chem.  Bull.  137,  p.  40. 
'"Ibid.,  105,  p.  166. 
"  Ibid.,  p.  167. 

^^  Fresenius.     Quantitative   Chemical  Analysis.     Revised  and  amplified  transla- 
tion of  the  6th  German  ed.,  2 :  1180;  U.  S.  Geol.  Surv,  Bull.  422,  p.  179. 
'^  Sutton.     Volumetric  Analysis.     10th  ed.,  1911,  p.  207. 
i<  Ibid.,  9th  ed.,  rev.,  p.  201. 

1^  Lewkowitsch.     Chemical  Technology  and  Analysis  of  Oils,  Fats  and  Waxes.   5th 
ed.,  1915,  3:  -348. 
'«Ibid.,  346. 

'^  Sutton.     Volumetric  Analysis.     10th  ed.,  1911,  p.  61. 
>«  U.  S.  Bur.  Animal  Industry,  Bull.  133. 

I'  Ber.,  1898,  31:  2979;  J.  Am.  Chem.  Soc,  1905,  27:  1183;  U.  S.  Bur.  Chem.  Bull. 
99,  p.  30;  132,  p.  49;  137,  p.  47. 

"  Z.  anal.  Chem.,  1897,  36:  18;  U.  S.  Bur.  Chem.  Bull.  132,  p.  49. 
"  J.  Assoc.  Official  Agr.  Chemists,  1915,  1 :  76. 
"  J.  Am.  Chem.  Soc,  1911,  33:  844. 
»  J.  Soc.  Chem.  Ind.,  1912,  31:  369. 


VIII.  FOODS  AND  FEEDING  STUFFS. 

1  PREPARATION  OF  SAMPLE.— OFFICIAL. 

Grind  the  sample  so  that  it  will  pass  through  a  sieve  having  circular  openings 
it  inch  (1  mm.)  in  diameter.  If  the  sample  can  not  be  ground,  reduce  it  to  as  fine  a 
state  as  possible. 


2  Direct  Drying. — Official. 

Dry  a  quantity  of  the  substance,  representing  about  2  grams  of  dry  material, 
in  a  current  of  dry  hydrogen  or  in  vacuo  at  the  temperature  of  boiling  water  to 
constant  weight  (approximately  5  hours).  If  the  substance  be  held  in  a  glass  vessel, 
the  latter  should  not  be  in  contact  with  the  boiling  water. 

3  Drying  in  Vacuo  without  Heat. — Tentative. 

Mix  the  sample  thoroughly  and  weigh  by  difference  2-5  gram  portions  from  a 
stoppered  weighing  bottle  into  tared,  covered  crucibles.  Where  subsequent  fat 
determinations  are  to  be  made,  fat  extraction  cones  may  be  used.  Substances  that 
dry  down  to  horn-like  material  should  be  mixed  with  fat-free  cotton  or  other  suit- 
able material  (previously  tared  with  the  container).  Place  200  cc.  of  fresh  concen- 
trated sulphuric  acid  in  a  strong,  tight  6  inch  vacuum  desiccator.  Put  triplicate 
samples  in  separate  desiccators,  and  exhaust  by  means  of  a  vacuum  pump.  If  a 
pump  is  not  available,  place  10  cc.  of  ether  in  a  small  beaker  in  the  desiccator,  and 
exhaust  with  a  water  filter  pump. 

Between  the  pump  and  the  desiccator  interpose  an  empty  bottle,  next  to  the 
desiccator,  and  a  bottle  of  water.  Draw  the  air  from  the  desiccator  through  the 
water  and  turn  the  desiccator  stop-cock  at  just  the  instant  when  the  water  begins 
to  rise  in  the  tube  leading  from  the  empty  bottle. 

Gently  rotate  the  desiccator  4  or  5  times  during  the  first  12  hours  to  mix  the  sul- 
phuric acid  with  the  water  which  has  collected  as  an  upper  layer.  At  the  end  of  24 
hours  open  the  desiccator,  forcing  the  incoming  air  to  bubble  through  concentrated 
sulphuric  acid,  and  make  the  first  weighing.  After  weighing  place  in  a  desiccator 
containing  fresh  concentrated  sulphuric  acid  and  exhaust  as  before.  Rotate  the 
desiccator  several  times  during  the  interval  and  weigh  again  after  a  suitable  period 
of  drying.  Repeat  this  process  of  drying  in  vacuo  over  sulphuric  acid  until  the 
weight  is  constant. 

4  ASH.— OFFICIAL. 

Char  a  quantity  of  the  substance,  representing  about  2  grams  of  the  dry  material, 
and  burn  until  free  from  carbon  at  a  low  heat,  not  to  exceed  dull  redness.  If  a 
carbon-free  ash  can  not  be  obtained  in  this  manner,  exhaust  the  charred  mass  with 
hot  water,  collect  the  insoluble  residue  on  a  filter,  burn  till  the  ash  is  white  or  nearly 
so,  and  then  add  the  filtrate  to  the  ash  and  evaporate  to  dryness.  Heat  to  low 
redness  till  the  ash  is  white  or  grayish  white  and  weigh. 

79 


80  METHODS    OF   ANALYSIS  [Chap. 

5  CRUDE  PROTEIN.-OFFICIAL. 

Determine  nitrogen  as  directed  under  I,  18,21,  or  23,  and  multiply  the  result  by 
6.25. 

ALBUMINOID  NITROGEN.— OFFICIAL. 

6  REAGENT. 

Stutzer's  reagent.— Frepare  cupric  hydroxid  as  follows:  Dissolve  100  grams  of  pure 
copper  sulphate  in  5  liters  of  water,  add  2.5  cc.  of  glycerol,  and  then  dilute  sodium 
hydroxid  solution  until  the  liquid  is  just  alkaline;  filter,  rub  the  precipitate  up  with 
water  containing  5  cc.  of  glycerol  per  liter,  and  wash  by  decantation  or  filtration 
until  the  washings  are  no  longer  alkaline.  Rub  the  precipitate  up  again  in  a  mortar 
with  water  containing  10%  of  glycerol,  thus  preparing  a  uniform  gelatinous  mass 
that  can  be  measured  with  a  pipette.  Determine  the  quantity  of  copper  hydroxid 
per  cc.  of  this  mixture. 

7  DETERMINATION. 

Place  0.7  gram  of  the  substance  in  a  beaker,  add  100  cc.  of  water,  and  heat  to 
boiling ;  or,  in  case  of  substances  rich  in  starch,  heat  on  the  water  bath  for  10  minutes ; 
add  a  quantity  of  the  Stutzer's  reagent  containing  about  0.5  gram  of  the  hydroxid; 
stir  thoroughly,  filter  when  cold,  wash  with  cold  water,  and,  without  removing  the 
precipitate  from  the  filter,  determine  the  nitrogen  according  to  I,  18,  21  or  23, 
adding  sufficient  potassium  sulphid  solution  to  completely  precipitate  all  of  the 
copper  and  mercury.  The  filter  paper  used  must  be  practically  free  from  nitrogen. 
If  the  material  (such  as  seeds,  seed  residue,  or  oil  cake)  is  rich  in  alkaline  phos- 
phates, add,  to  decompose  the  alkaline  phosphates,  1-2  cc.  of  a  concentrated  potash 
or  soda  alum  solution,  free  from  ammonia,  then  the  copper  hydroxid,  and  mix  well 
by  stirring.  If  this  is  not  done,  copper  phosphate  and  free  alkali  may  be  formed, 
and  the  protein-copper  precipitate  partially  dissolved  in  the  alkaline  liquid. 

8  AMIDO  NITROGEN.-OFFICDa. 

Subtract  the  amount  of  albuminoid  nitrogen  from  the  amount  of  total  nitrogen 
to  obtain  the  amido  nitrogen. 

CRUDE  FAT  OR  ETHER  EXTRACT. 

Direct  Method. — Official. 


Anhydrous  ether. — Wash  any  of  the  commercial  brands  of  ether  with  2  or  3  suc- 
cessive portions  of  water,  add  solid  sodium  or  potassium  hydroxid,  and  let  stand 
until  most  of  the  water  has  been  abstracted  from  the  ether.  Decant  into  a  dry 
bottle,  add  small  pieces  of  carefully  cleaned  metallic  sodium,  and  let  stand  until 
there  is  no  further  evolution  of  hydrogen  gas.  Keep  the  ether,  thus  dehydrated, 
over  metallic  sodium  in  lightly  stoppered  bottles. 

10  DETERMINATION. 

Large  quantities  of  soluble  carbohydrates  may  interfere  with  the  complete  ex- 
traction of  the  fat.  In  such  cases  extract  with  water  before  proceeding  with  the 
determination.  Extract  about  2  grams  of  material,  dried  as  under  2  or  3,  with  the 
anhydrous  ether  for  16  hours.  Dry  the  extract  at  the  temperature  of  boiling  water 
for  30  minutes,  cool  in  a  desiccator,  and  weigh;  continue,  at  30  minutes  intervals, 
this  alternate  drying  and  weighing  to  constant  weight.  For  most  feeds  a  period 
of  1-1  i  hours  is  required. 


Vni]  FOODS   AND    FEEDING    STUFFS  81 

11  Indirect  Method. — Official. 

Determine  the  moisture,  as  directed  in  2  or  3,  then  extract  the  dried  substance 
for  16  hours  as  directed  under  10,  dry  again  and  regard  the  loss  of  weight  as  ether 
extract. 

Sucrose. 

OPTICAL  METHODS. 

1 2  GENERAL  DIRECTIONS  FOR  RAW  SUGARS— TENTATIVE. 

(Rules'  of  the  International  Commission  for  Unifying  Methods  of  Sugar  Analysis.) 

"In  general  all  polarizations  are  to  be  made  at  20°C." 

"The  verification  of  the  saccharimeter  must  also  be  made  at  20°C.  For  instru- 
ments using  the  Ventzke  scale  26  grams  of  pure  dry  sucrose,  weighed  in  air  with 
brass  weights,  dissolved  in  100  metric  cc.  at  20°C.  and  polarized  in  a  room,  the  tem- 
perature of  which  is  also  20°C.,  must  give  a  saccharimeter  reading  of  exactly  100.00. 
The  temperature  of  the  sugar  solution  during  polarization  must  be  kept  constant 
at  20°C." 

"For  countries  where  the  mean  temperature  is  higher  than  20°C.,  saccharimeters 
may  be  adjusted  at  30°C.  or  any  other  suitable  temperature,  under  the  conditions 
specified  above,  provided  that  the  sugar  solution  be  made  up  to  volume  and  polarized 
at  this  same  temperature." 

"In  effecting  the  polarization  of  substances  containing  sugar  employ  only  half- 
shade  instruments."  The  saccharimeter  used  can  be  either  single  or  double  wedge 
and  should  be  a  half-shadow  instrument  with  either  double  or  triple  field. 

"During  the  observation  keep  the  apparatus  in  a  fixed  position  and  so  far  removed 
from  the  source  of  light  that  the  polarizing  Nicol  is  not  warmed." 

"As  sources  of  light  employ  lamps  which  give  a  strong  illumination  such  as 
triple  gas  burner  with  metallic  cylinder,  lens  and  reflector;  gas  lamps  with  Auer 
(Welsbach)  burner;  electric  lamp;  petroleum  duplex  lamp;  sodium  light."  When- 
ever there  is  any  irregularity  in  the  sources  of  light  such  as  that  due  to  the  convolu- 
tions of  the  filament  in  the  case  of  electric  light  or  to  the  meshes  of  the  gauze  in  the 
case  of  the  Welsbach  light,  place  a  thin  ground-glass  plate  between  the  source  of 
light  and  the  polariscope  so  as  to  render  the  illumination  uniform. 

"Before  and  after  each  set  of  observations  the  chemist  must  satisfy  himself  of  the 
correct  adjustment  of  his  saccharimeter  by  means  of  standardized  quartz  plates. 
He  must  also  previously  satisfy  himself  of  the  accuracy  of  his  weights,  polarization 
flasks,  observation  tubos  and  cover-glasses.  (Scratched  cover-glasses  must  not  be 
used.)  Make  several  readings  and  take  the  mean  thereof,  but  no  one  reading  may 
be  neglected."  Such  plates  are  standardized  to  read  to  the  second  decimal  point 
and  by  their  use  a  quick  and  at  the  same  time  accurate  test  can  be  made.  In  using 
such  plates  for  testing  saccharimeters,  it  is  necessary  that  the  instrument,  as  well  as  the 
plate,  be  at  20°C.  before  making  a  reading.  Different  points  of  the  scale,  preferably 
20°,  50°,  80°,  and  100°,  (sugar  scale)  should  be  tested  against  the  plates. 

"In  making  a  polarization  use  the  whole  normal  weight  for  100  cc.  or  a  multiple 
thereof  for  any  corresponding  volume." 

"As  clarifying  and  decolorizing  agents  use  cither  basic  acetate  of  lead,  alumina 
cream,  or  concentrated  solution  of  alum.  Boneblack  and  decolorizing  powders  are 
to  be  excluded."  Whenever  reducing  sugars  are  determined  in  the  solution  for  po- 
larizing, use  only  neutral  lead  acetate  for  clarification  as  basic  lead  acetate  causes 
precipitation  of  some  of  the  reducing  sugars.     In  addition  to  these  clarifying  agents, 


82  METHODS    OF   ANALYSIS  [Chap. 

neutral  lead  acetate  and  basic  lead  nitrate  (Herles'  solution)  have  been  made  official 
by  the  Association. 

"After  bringing  the  solution  exactly  to  the  mark  at  the  proper  temperature,  and 
after  wiping  out  the  neck  of  the  flask  with  filter  paper,  pour  all  of  the  well-shaken 
clarified  sugar  solution  on  a  rapidly  acting  filter.  Reject  the  first  portions  of  the 
filtrate,  and  use  the  rest,  which  must  be  perfectly  clear,  for  polarization."  It  is 
advisable  to  reject  the  first  20  cc.  that  run  through,  then  cover  the  funnel  with  a 
watch  glass  and  use  the  remainder  for  polarization.  In  no  case  should  the  whole 
solution  or  any  part  be  returned  to  the  filter.  If  cloudy  after  the  20  cc.  have  been 
rejected,  begin  a  new  determination. 

"Whenever  white  light  is  used  in  polarimetric  determinations,  the  same  must  be 
filtered  through  a  solution  of  potassium  dichromate  of  such  a  concentration  that  the 
percentage  content  of  the  solution  multiplied  by  the  length  of  the  column  of  the  solu- 
tion in  centimeters  is  equal  to  nine."  This  concentration  must  be  doubled  in 
reading  carbohydrate  materials  of  high  rotation  dispersion,  such  as  commercial 
glucose,  etc. 

13  PREPARATION  AND  USE  OF  CLARIFYING  REAGENTS.— TENTATIVE. 

(a)  Basic  lead  acetate  solution. — Boil  430  grams  of  neutral  lead  acetate,  130  grams 
of  litharge,  and  1  liter  of  water  for  30  minutes.  Allow  the  mixture  to  cool  and  settle 
and  dilute  the  supernatant  liquid  to  a  specific  gravity  of  1.25  with  recently  boiled 
water.  Solid  basic  lead  acetate  may  be  substituted  for  the  normal  salt  and  litharge 
in  the  preparation  of  the  solution. 

(b)  Ahimina  cream. — Prepare  a  cold  saturated  solution  of  alum  in  water.  Add 
ammonium  hydroxid  with  constant  stirring  until  the  solution  is  alkaline  to  litmus, 
allow  the  precipitate  to  settle  and  wash  by  decantation  with  water  until  the  wash 
water  gives  only  a  slight  test  for  sulphates  with  barium  chlorid  solution.  Pour  off 
the  excess  of  water  and  store  the  residual  cream  in  a  stoppered  bottle. 

(C)  Dry  basic  lead  acetate  {Home  method). — This  clarifying  agent  is  obtained  as 
a  dry  powdered  salt  and  should  contain  72.8%  of  lead,  which  corresponds  to  a  com- 
position of  3Pb(C2H302)22PbO.  Dissolve  the  normal  or  half -normal  weight  of  the 
sugar  solution  in  a  flask  with  water  and  complete  the  volume.  Add  a  small  quantity 
of  the  dry  salt  and  shake,  then  add  more  and  shake  again,  repeating  until  completely 
precipitated  but  avoiding  any  excess.  Of  this  salt  0.1346  gram  is  equivalent  to  1  cc. 
of  the  basic  lead  acetate  solution,  described  under  (a).  When  molasses  or  any  other 
substance  producing  a  heavy  precipitate  is  being  clarified,  some  dry,  coarse  sand 
should  be  added  to  break  up  the  balls  of  basic  lead  acetate  and  the  precipitate. 
(This  method  is  to  have  equal  weight  with  the  use  of  a  solution  of  basic  lead  acetate 
in  clarifying  cane,  sorghum,  and  beet  products.) 

(d)  Neutral  lead  acetate. — Prepare  a  saturated  solution  of  neutral  lead  acetate  and 
add  it  to  the  sugar  solution  before  completing  to  volume.  Its  use  is  imperative  when 
determining  the  reducing  sugars  in  the  solution  used  for  polarization. 

(e)  Basic  lead  nitrate  {Merles'  solution). — (1)  Dissolve  250  grams  of  lead  nitrate 
in  water  and  make  up  to  500  cc.  (2)  Dissolve  25  grams  of  sodium  hydroxid  in  water 
and  make  up  to  500  cc. 

Add  equal  amounts  of  (1)  and  (2)  to  the  sugar  solution,  shake,  and  add  more  if 
complete  precipitation  has  not  occurred,  but  avoid  any  excess.  Then  complete 
the  volume  with  water.  When  this  solution  is  used  for  clarification,  the  factor  in  the 
Clerget  determination  becomes  143.5  instead  of  142.66. 


Vni]  FOODS   AND    FEEDING    STUFFS  83 

DETERMINATION  OF  SUCROSE  IN  THE  ABSENCE  OF  RAFFINOSE. 

(In  the  presence  of  much  levulose,  as  in  honeys  and  fruits  products,  the  optical 
method  for  sucrose  gives  too  high  a  result.) 

14      By  Polarization  Before  and  After  Inversion  with  Hydrochloric  Acid. — Official. 

Dissolve  the  normal  weight  (26  grams)  of  the  substance  in  water,  add  basic  lead 
acetate  carefully,  avoiding  any  excess,  then  1-2  cc.  of  alumina  cream,  shake,  and 
dilute  to  100  metric  cc,  filter,  rejecting  the  first  20  cc.  of  the  filtrate,  cover  the 
filter  with  a  watch  glass  and,  when  sufficient  filtrate  is  collected,  polarize  in  a  200 
mm.  tube.  The  reading  so  obtained  is  the  direct  reading  (P  of  formula  given  be- 
low) or  polarization  before  inversion.  For  the  invert  reading,  remove  the  lead  from 
the  solution  either  (1)  by  adding  anhydrous  potassium  oxalate,  a  little  at  a  time, 
to  the  remaining  solution,  avoiding  an  excess  and  removing  the  precipitated  lead 
by  filtration;  or,  (2)  by  adding  anhydrous  sodium  carbonate  under  the  same  con- 
ditions. Introduce  50  cc.  of  the  lead-free  filtrate  into  a  100  cc.  flask  (if  sodium 
carbonate  was  used  for  removing  the  lead,  neutralize  carefully  the  excess  of  sodium 
carbonate  with  a  few  drops  of  dilute  hydrochloric  acid)  and  add  25  cc.  of  water. 
Then  add,  little  by  little,  while  rotating  the  flask,  5  cc.  of  hydrochloric  acid,  (sp.gr. 
1.20).  Heat  the  flask  after  mixing,  in  a  water  bath  kept  at  70°C.  The  temperature 
of  the  solution  in  the  flask  should  reach  67°-69°C.  in  2|-3  minutes.  Maintain  a 
temperature  of  as  nearly  69°C.  as  possible  for  7-7J  minutes,  making  the  total  time 
of  heating  10  minutes.  Remove  the  flask  and  cool  the  contents  rapidly  to  20°C. 
and  dilute  to  100  cc.  Polarize  this  solution  in  a  tube  provided  with  a  lateral  branch 
and  a  water  jacket,  maintaining  a  temperature  of  20°C.  This  reading  must  be 
multiplied  by  2  to  obtain  the  invert  reading.  If  it  is  necessary  to  work  at  a  tem- 
perature other  than  20°C.,  which  is  allowable  within  narrow  limits,  the  volumes 
must  be  completed  and  both  direct  and  invert  polarizations  must  be  made  at  exactly 
the  same  temperature. 

The  inversion  may  also  be  accomplished  as  follows:  (1)  To  50  cc.  of  the  clarified 
solution,  freed  from  lead,  add  5  cc.  of  hydrochloric  acid  (sp.  gr.  1.20)  and  set  aside 
for  24  hours  at  a  temperature  not  below  20°C.;  or  ,(2)  If  the  temperature  be  above 
25°C.  set  aside  for  10  hours.  Make  up  to  100  cc.  at  20°C.  and  polarize  as  directed 
above. 

Calculate  sucrose  by  one  of  the  following  formulas: 

For  substances  in  which  the  invert  solution  contains  more  than  12  grams  of  invert 
sugar  per  100  cc. — The  following  formula  is  to  be  used  when  substances  like  raw 
sugars  are  polarized: 

^       100  (P  -  I)  .       ,  .  , 

S  =  in  which 

T 
142.66  -  - 

S  =  per  cent  of  sucrose; 

P  =  direct  reading  normal  solution ; 

I    =  invert  reading  normal  solution; 

T  =  temperature  at  which  readings  are  made. 
For  substances  in  lohich  the  concentration  of  the  invert  solution  is  less  than  12  grams 
■per  100  cc. — The  following  formula,  which  takes  into  account  the  concentration  of  the 
sugar  in  solution,  should  be  used  in  all  other  cases. 


84  METHODS   OF  ANALYSIS  [Chap. 


100  (P  -  I)  •        u-  u 

S  =  =^ p Fp ^  in  which 

142.66  -  2  -  0-0065  [142.66  -  ^  -  (P 


S  =  per  cent  of  sucrose; 
P  =  direct  reading  normal  solution; 
I  =  invert  reading  normal  solution; 
T  =  temperature. 

Bt/  Polarization  Before  and  After  Inversion  with  Invertase.— Tentative. 

15  REAGENT. 

Invertase  solution  (Hudson  Method.^)— Mix  1  kilo  of  pressed  baker's  or  brewer's 
yeast  with  1  liter  of  tap  water  and  50  cc.  of  toluene  and  keep  at  room  temperature 
2-3  days  to  allow  autolysis  to  proceed  to  the  stage  of  maximum  inverting  activity. 
Then  add  neutral  lead  acetate  in  slight  excess,  filter,  precipitate  the  lead  in  the 
filtrate  with  hydrogen  sulphid,  filter  again  and  then  dialyze  the  filtrate  thoroughly 
in  a  collodion  sac.  Preserve  in  an  ice  box  the  dialyzed  solution  with  the  addition 
of  a  little  toluene  to  prevent  the  growth  of  micro-organisms.  Note  the  optical 
activity  of  the  invertase  solution  and  correct  the  invert  reading  according  to  the 
amount  of  the  solution  used. 

1 6  DETERMINATION. 

Dissolve  the  normal  weight  (26  grams)  of  the  substance  in  water,  clarify,  make 
up  to  volume,  and  take  the  direct  polarization  (P)  as  directed  under  14.  If  lead 
has  been  used  as  a  clarifying  agent,  remove  the  excess  of  lead  from  the  filtrate,  with 
anhydrous  sodium  carbonate  or  potassium  oxalate,  and  filter.  To  50  cc.  of  the 
filtrate  in  a  100  cc.  flask  add  acetic  acid,  drop  by  drop,  until  the  reaction  is  acid  to 
litmus,  add  10  cc.  of  the  invertase  solution,  fill  the  flask  with  water  nearly  to  100  cc. 
and  let  stand  in  a  warm  place  (about  40°C.)  overnight.  Cool  and  make  up  to  100  cc. 
at  20°C.  Polarize  at  20°C.  in  a  200  mm.  tube.  Allow  the  solution  to  remain  in  the 
tube  for  an  hour  and  repeat  the  polarization.  If  there  is  no  change  from  the  pre- 
vious reading,  the  inversion  is  complete,  whereupon  the  reading  and  temperature 
of  the  solution  are  carefully  noted.  Correct  the  reading  for  the  optical  activity 
of  the  invertase  solution  and  then  multiply  by  2.  Calculate  the  percentage  of 
sucrose  by  the  following  formula: 

100  (P  -  I)  .        ... 

in  which 


142 0.0065  1142 (P 

2  L  2 


■'] 


S  =  per  cent  of  sucrose; 

P  =«  direct  reading; 

I    =  invert  reading; 

T  =  temperature  at  which  invert  reading  is  made. 

17  DETERMINATION  OF  SUCROSE  AND  RAFFINOSE.-OFFICIAL. 

(Of  value  chiefly  in  the  analysis  of  beet  products.) 

If  the  direct  reading  is  more  than  1°  higher  than  the  per  cent  of  sucrose  as  -  al- 
culated  by  the  formula  given  under  14,  raffinose  is  probably  present.  Calculate 
sucrose  and  raffinose  by  the  following  formula  of  Herzfeld: 


Vin]  FOODS  AND  FEEDING  STUFFS  85 

„       0.5124  P-I  ^        P-S  . 

S  = :        R  = in  which 

0.839        '  1.852 

P  =  direct  reading  normal  solution; 
I  =  invert  reading  normal  solution; 
S  =  per  cent  of  sucrose; 
R  =  per  cent  of  anhydrous  raffinose. 

The  above  formula  assumes  that  the  polarizations  are   made  at  exactly  20°C. 
If  the  temperature  (T)  is  other  than  20°C.,  the  following  formula  should  be  used: 

P  (0.4724  +  0-002  T)  -  I 
0.899  -  0.003  T 

P-S 


Having  calculated  S,  then  R  = 


1.852 
CHEMICAL  METHODS. 

1  8      DETERMINATION  OF  SUCROSE  FROM  REDUCING  SUGARS  BEFORE  AND  AFTER 
INVERSION.— TENTATIV  E. 

Determine  the  reducing  sugars  (clarification  having  been  effected  with  neutral 
lead  acetate,  never  with  basic  lead  acetate),  as  directed  under  25,  and  calculate  to 
invert  sugar  from  27.  Invert  the  solution  as  directed  under  14  or  16,  exactly 
neutralize  the  acid,  and  again  determine  the  reducing  sugars,  but  calculate  them 
to  invert  sugar  from  the  same  table  as  referred  to  above,  using  the  invert  sugar 
column  alone.  Deduct  the  percentage  of  invert  sugar  obtained  before  inversion 
from  that  obtained  after  inversion,  and  multiply  the  difference  by  0.95,  the  result 
being  the  per  cent  of  sucrose.  The  solutions  should  be  diluted  in  both  determina- 
tions so  that  not  more  than  245  mg.  of  invert  sugar  are  present  in  the  amount 
taken  for  reduction.  It  is  important  that  all  lead  be  removed  from  the  solution 
with  potassium  oxalate  before  reduction. 

Reducing  Sugars, 
invert  sugar. 

Approximate  Volumetric  Method  for  Rapid  Work. — Tentative. 

19  REAGENT. 

Soxhlet's  Modification  of  Fehling's  Solution. — Prepare  by  mixing,  immediately 
before  use.  equal  volumes  of  (a)  and  (b). 

(a)  Copper  sulphate  solution. — Dissolve  34.639  grams  of  copper  sulphate  (CuSO^ 
5H2O)  in  water,  dilute  to  500  cc.  and  filter  through  prepared  asbestos. 

(b)  Alkaline  tartrate  solution. — Dissolve  173  grams  of  Rochelle  salts  and  50  grams 
of  sodium  hydroxid  in  water,  dilute  to  500  cc,  allow  to  stand  for  2  days  and  filter 
through  prepared  asbestos. 

20  STAND.^RDIZATION    OF   COPPER   SOLUTION. 

Since  the  factor  of  calculation  varies  with  the  minute  details  of  manipulation, 
every  operator  must  determine  a  factor  for  himself,  using  a  known  solution  of  the 
pure  sugar  that  he  desires  to  determine,  and  keeping  the  conditions  the  same  as 
those  used  for  the  detern^ination. 


86  METHODS    OF   ANALYSIS  [Chap. 

Standardize  the  solution  for  invert  sugar  in  the  following  manner: 
Dissolve  4.75  grams  of  pure  sucrose  in  75  cc.  of  water,  add  5  cc.  of  hydrochloric 
acid  (sp.  gr.  1.20)  and  invert  as  directed  under  14.  Neutralize  the  acid  with  sodium 
hydroxid  solution  and  dilute  to  1  liter.  Ten  cc.  of  this  solution  contain  0.050  gram  of 
invert  sugar,  which  should  reduce  10  cc.  of  the  reagent.  The  strength  of  the  copper 
solution  should  never  be  taken  as  a  constant,  but  should  be  checked  against  the 
sugar. 


21 


DETERMINATION. 


Place  10  CC.  of  the  reagent  in  a  large  test  tube  and  add  10  cc.  of  water.  Heat  to 
boiling,  and  add  gradually  small  portions  of  the  solution  of  the  material  to  be  tested 
until  the  copper  has  been  completely  reduced,  boiling  after  each  addition  to  com- 
plete the  reaction.  Two  minutes'  boiling  is  required  for  complete  reduction  when 
the  full  amount  of  sugar  solution  has  been  added  in  one  portion.  When  the  end 
is  nearly  reached  and  the  amount  of  sugar  solution  to  be  added  can  no  longer  be 
judged  by  the  color  of  the  solution,  remove  a  small  portion  of  the  liquid  and  filter 
rapidly  into  a  small  porcelain  crucible  or  on  a  test  plate;  acidify  with  dilute  acetic 
acid,  and  test  for  copper  with  dilute  potassium  ferrocyanid  solution.  The  sugar 
solution  should  be  of  such  strength  as  will  give  a  burette  reading  of  15-20  cc,  and 
the  number  of  successive  additions  should  be  as  small  as  possible. 

Soxhlet  Volumetric  Method. — Tentative. 

22  REAGENT. 

The  reagent  used  is  described  under  19. 

23  DETERMINATION. 

Make  a  preliminary  titration  to  determine  the  approximate  percentage  of  reduc- 
ing sugar  in  the  material  under  examination.  Prepare  a  solution  which  contains 
approximately  1%  of  reducing  sugar.  Place  in  a  beaker  100  cc.  of  the  reagent  and 
approximately  the  amount  of  the  sugar  solution  for  its  complete  reduction.  Boil 
for  2  minutes.  Filter  through  a  folded  filter  and  test  a  portion  of  the  filtrate  for 
copper  by  use  of  dilute  acetic  acid  and  dilute  potassium  ferrocyanid  solution.  Re- 
peat, varying  the  volume  of  sugar  solution,  until  2  successive  amounts  are  found 
which  differ  by  0.1  cc,  one  giving  complete  reduction  and  the  other  leaving  a  small 
amount  of  copper  in  solution.  The  mean  of  these  2  readings  is  taken  as  the  volume 
of  the  solution  required  for  the  complete  precipitation  of  100  cc.  of  the  reagent. 

Under  these  conditions  100  cc.  of  the  reagent  require  0.494  gram  of  invert  sugar 
for  complete  reduction.     Calculate  the  percentage  by  the  following  formula: 

V  =  the  volume  of  the  sugar  solution  required  for  the  complete  reduction  of 

100  cc.  of  the  reagent; 

W  =  the  weight  of  the  sample  in  1  cc.  of  the  sugar  solution; 

100  X  0.494  \    t  ■       ^ 

— — =  per  cent  of  mvert  sugar. 

VW 

GRAVIMETRIC  METHODS 

Munson  and  Walker  General  Methods — Tentative. 

24  REAGENTS. 

(a)  Asbestos. — Digest  the  asbestos,  which  should  be  the  amphibole  variety,  with 
dilute  hydrochloric  acid  (1  to  3)  for  2-3  days.     Wash  free  from  acid,  digest  for  a 


Vin]  FOODS  AND  FEEDING  STUFFS  87 

similar  period  with  10%  sodium  hydroxid  solution,  and  then  treat  for  a  few  hours 
with  hot  alkaline  tartrate  solution  (old  alkaline  tartrate  solutions  that  have  stood 
for  some  time  may  be  used  for  this  purpose)  of  the  strength  employed  in  sugar  de- 
terminations. Then  wash  the  asbestos  free  from  alkali,  digest  for  several  hours 
with  dilute  nitric  acid  (1  to  3)  and,  after  washing  free  from  acid,  shake  with  water 
into  a  fine  pulp.  In  preparing  the  Gooch  crucible,  make  a  film  of  asbestos  i  inch 
thick  and  wash  thoroughly  with  water  to  remove  fine  particles  of  asbestos.  If  the 
precipitated  cuprous  oxid  is  to  be  weighed  as  such,  wash  the  crucible  with  10  cc.  of 
alcohol,  then  with  10  cc.  of  ether,  dry  for  30  minutes  at  100°C.,  cool  in  a  desiccator 
and  weigh. 

(b)  The  solution  used  is  described  under  19. 

25  PRECIPITATION   OF  CUPROUS   OXID. 

Transfer  25  cc.  each  of  the  copper  sulphate  and  alkaline  tartrate  solutions  to  a 
400  cc.  beaker  of  alkali-resisting  glass  and  add  50  cc.  of  reducing  sugar  solution,  or, 
if  a  smaller  volume  of  sugar  solution  is  used,  add  water  to  make  the  final  volume 
100  cc.  Heat  the  beaker  upon  an  asbestos  gauze  over  a  Bunsen  burner,  regulate  the 
flame  so  that  boiling  begins  in  4  minutes,  and  continue  the  boiling  for  exactly  2 
minutes.  (It  is  important  that  these  directions  be  strictly  observed  and,  in  order 
to  regulate  the  burner  for  this  purpose,  it  is  advisable  to  make  preliminary  tests, 
using  50  cc.  of  the  reagent  and  50  cc.  of  water  before  proceeding  with  the  actual 
determination.)  Keep  the  beaker  covered  with  a  watch  glass  during  the  heating. 
Filter  the  cuprous  oxid  at  once  on  an  asbestos  mat  in  a  porcelain  Gooch  crucible, 
using  suction.  Wash  the  cuprous  oxid  thoroughly  with  water  at  a  temperature  of 
about  60°C.,  and  either  weigh  directly  as  cuprous  oxid  as  in  26,  or,  determine  the 
amount  of  reduced  copper  by  one  of  the  methods  under  29-34,  respectively.  Con- 
duct a  blank  determination,  using  50  cc.  of  the  reagent  and  50  cc.  of  water,  and,  if 
the  weight  of  cuprous  oxid  obtained  exceeds  0.5  mg.,  correct  the  result  of  the  reducing 
sugar  determination  accordingly.  The  alkaline  tartrate  solution  deteriorates  on 
standing  and  the  amount  of  cuprous  oxid  obtained  in  the  blank  increases. 

Determination  of  Reduced  Copper. 

26  7.    Direct  Weighing  of  Cuprous  Oxid. — Tentative. 

Prepare  a  Gooch  as  directed  under  24  (a). 

Collect  the  precipitated  cuprous  oxid  on  the  mat,  as  directed  under  25,  wash 
thoroughly  with  hot  water,  then  with  10  cc.  of  alcohol,  and  finally  with  10  cc.  of 
ether.  Dry  the  precipitate  for  30  minutes  in  a  water  oven  at  the  temperature  of 
boiling  water;  cool  and  weigh.  Calculate  the  weight  of  metallic  copper.  Obtain 
from  27  the  weight  of  invert  sugar  equivalent  to  the  weight  of  copper  found. 

This  method  should  be  used  only  for  determinations  in  pure  sugar  solutions.  In 
all  other  products  the  copper  of  the  cuprous  oxid  should  be  determined  by  one  of  the 
following  methods,  since  the  cuprous  oxid  is  very  apt  to  be  contaminated  with 
foreign  matter. 

The  number  of  milligrams  of  copper  reduced  by  a  given  amount  of  reducing  sugar 
differs  when  sucrose  is  present  and  when  it  is  absent.  In  the  tables  the  absence  of 
sucrose  is  assumed  except  in  the  two  columns  under  invert  sugar,  where  one  for 
mixtures  of  invert  sugar  and  sucrose  containing  0.4  gram  of  total  sugar  in  50  cc.  of 
solution,  and  one  for  invert  sugar  and  sucrose  when  the  50  cc.  of  solution  contains  2 
grams  of  total  sugar  are  given,  in  addition  to  the  column  for  invert  sugar  alone. 


METHODS   OF   ANALYSIS 


[Chap. 


27 


Table  1.— Munson  and  Walker's  Table. 


For  calculating  dextrose,  invert  sugar  alone,  invert  sugar  in  the  presence  of  sucrose 
{0.4  gram  and  2  grains  total  sugar),  lactose  {'wo  forms),  and  maltose  {anhydrous  and 
crystallized). 

(Expressed  in  milligrams.] 


o 

"w 

INVERT  SUGAR 

LACTI 

SE 

MALTOSE            1 

6 

3 

o 

AND  8CCROSE 

6 

o 

0 

0 

.J 

K 

1 

3 

q 

O 

o 

s 

o 

"a 

O 

t 
o 

1 

K 

I 

> 

la 

o 

1 

6 

3 

1 
6 

o 

10 

8.9 

4.0 

4.5 

1.6 

3.8 

4.0 

5.9 

6.2 

11 

9.8 

4.5 

5.0 

4.5 

4.7 

6.7 

7.0 

12 

10.7 

4.9 

5.4 

2.5 

5.1 

5.4 

7.5 

7.9 

13 

11.5 

5.3 

5.8 

3.0 

5.8 

6.1 

8.3 

8.7 

14 

12.4 

5.7 

6.3 

3.4 

6.4 

6.8 

9.1 

9.5 

15 

13  3 

6.2 

6.7 

3.9 

7.1 

7.5 

9.9 

10.4 

16 

14.2 

6.6 

7.2 

4.3 

7.8 

8.2 

10.6 

11.2 

17 

15.1 

7.0 

7.6 

4.8 

8.4 

8.9 

11.4 

12.0 

18 

16.0 

7.5 

8.1 

5.2 

9.1 

9.5 

12.2 

12.9 

19 

16.9 

7.9 

8.5 

5.7 

9.7 

10.2 

13.0 

13.7 

20 

17.8 

8.3 

8.9 

6.1 

10.4 

10.9 

13.8 

14.6 

21 

18.7 

8.7 

9.4 

6.6 

11.0 

11.6 

14.6 

15.4 

22 

19.5 

9.2 

9.8 

7.0 

11.7 

12.3 

15.4 

18.2 

22 

23 

20.4 

9.6 

10.3 

7.5 

12.3 

13.0 

16.2 

17.1 

23 

24 

21.3 

10.0 

10.7 

7.9 

13.0 

13.7 

17.0 

17.9 

24 

25 

22.2 

10.5 

11.2 

8.4 

13.7 

14.4 

17.8 

18.7 

25 

26 

23.1 

10.9 

11.6 

8.8 

14.3 

15.1 

18.6 

19.6 

28 

27 

24.0 

11.3 

12.0 

9.3 

15.0 

15.8 

19.4 

20.4 

27 

28 

24.9 

11.8 

12.5 

9.7 

15.6 

16.5 

20.2 

21.2 

28 

29 

25.8 

12.2 

12.9 

10.2 

16.3 

17.1 

21.0 

22.1 

29 

30 

26.6 

12.6 

13.4 

10.7 

4.3 

16.9 

17.8 

21.8 

22.9 

30 

31 

27.5 

13.1 

13.8 

11.1 

4.7 

17.6 

18.5 

22.6 

23.7 

31 

32 

28.4 

13.5 

14.3 

11.6 

5.2 

18.3 

19.2 

23.3 

24.6 

32 

33 

29.3 

13.9 

14.7 

12.0 

5.6 

18.9 

19.9 

24.1 

25.4 

33 

34 

30.2 

14.3 

15.2 

12.5 

6.1 

19.6 

20.6 

24.9 

26.2 

34 

35 

31.1 

14.8 

15.6 

12.9 

6.5 

20.2 

21.3 

25.7 

27.1 

35 

36 

32.0 

15.2 

16.1 

13.4 

7.0 

20.9 

22.0 

26.5 

27.9 

36 

37 

32.9 

15.6 

16.5 

13.8 

7.4 

21.5 

22.7 

27.3 

28.7 

37 

38 

33.8 

16.1 

16.9 

14.3 

7.9 

22.2 

23.4 

28.1 

29.6 

38 

39 

34.6 

16.5 

17.4 

14.7 

8.4 

22.8 

24.1 

28.9 

30.4 

39 

40 

35.5 

16.9 

17.8 

15.2 

8.8 

23.5 

24.8 

29.7 

31.3 

40 

41 

36.4 

17.4 

18.3 

15.6 

9.3 

24.2 

25.4 

30.5 

32.1 

41 

42 

37.3 

17.8 

18.7 

16.1 

9.7 

24.8 

26.1 

31.3 

32  9 

42 

43 

38.2 

18.2 

19.2 

16.6 

10.2 

25.5 

26.8 

32.1 

33.8 

43 

44 

39.1 

18.7 

19.6 

17.0 

10.7 

26.1 

27.5 

32.9 

34.6 

44 

45 

40.0 

19.1 

20.1 

17.5 

11.1 

26.8 

28.2 

33.7 

35.4 

45 

46 

40.9 

19.6 

20.5 

17.9 

11.6 

27.4 

28.9 

34.4 

36.3 

46 

47 

41.7 

20.0 

21.0 

18.4 

12.0 

28.1 

29.6 

35  2 

37.1 

47 

48 

42.6 

20.4 

21.4 

18.8 

12.5 

28.7 

30.3 

36.0 

37.9 

48 

49 

43.5 

20.9 

21.9 

19.3 

12.9 

29.4 

31.0 

36.8 

38.8 

49 

50 

44.4 

21.3 

22.3 

19.7 

13.4 

30.1 

31.7 

37.6 

39.6 

50 

51 

45.3 

21.7 

22  8 

20.2 

13.9 

30.7 

32.4 

38.4 

40.4 

51 

52 

46  2 

22.2 

23.2 

20.7 

14.3 

31.4 

33  0 

39.2 

41.3 

52 

53 

47.1 

22.6 

23.7 

21.1 

14.8 

32.1 

33.7 

40.0 

42.1 

53 

54 

48.0 

23.0 

24.1 

21.6   . 

15.2 

32.7 

34.4 

40.8 

42.9 

54 

55 

48.9 

23.5 

24.6 

22.0 

15.7 

33.4 

35.1 

41.6 

43.8 

55 

56 

49.7 

23.9 

25.0 

22.5 

16.2 

34.0 

35.8 

42.4 

44.6 

56 

57 

50.6 

24  3 

25.5 

22.9 

16.6 

34.7 

36.5 

43.2 

45.4 

57 

58 

51.5 

24.8 

25.9 

23.4 

17.1 

35.4 

37.2 

44  0 

46.3 

58 

59 

52.4 

25.2 

26.4 

23.9 

17.5 

36.0 

37.9 

44.8 

47.1 

59 

60 

53.3 

25.6 

26.8 

24.3 

18.0 

36.7 

38.6 

45.6 

48.0 

60 

61 

54.2 

26.1 

27.3 

24.8 

18.5 

37.3 

39.3 

46.3 

48.8 

61 

62 

55.1 

26.5 

27.7 

25.2 

18.9 

38.0 

40.0 

47.1 

49.6 

62 

63 

56.0 

27.0 

28.2 

25.7 

19  4 

38.6 

40.7 

47.9 

50.5 

63 

64 

56.8 

27.4 

28.6 

26.2 

19.8 

39.3 

41.4 

48.7 

51.3 

64 

vm] 

27 


FOODS   AND    FEEDING    STUFFS 


Table  1.— Munson  and  Walker's  Table.- 

[Expressed  in  milligrams.) 


-Continued. 


1 

i 

INVERT  80'  AR 
AND  SUCROSE 

LACTOSE 

MALT    8E 

a 

o 

p 

o 

T' 

.J 

M 

1 

3 

a 

? 

O 

o 

o 

o 

o 

U 

s 

a  1- 

§ 

o 

s 

PS 

§ 

la 

O 

6 

6 

6 

o 

a 

s: 

;l 

s: 

^ 

3 

u 

O 

Q 

1 

a 
> 

M  3 

6 

w 
6 

6 

65 

57.7 

27.8 

29.1 

26.6 

20.3 

40.0 

42.1 

49.5 

52.1 

65 

66 

58.6 

28  3 

29.5 

27.1 

20.8 

40.6 

42.8 

50.3 

53.0 

66 

67 

59.5 

28.7 

30.0 

27.5 

21.2 

41.3 

43.5 

51.1 

53.8 

67 

68 

60.4 

29.2 

30.4 

28.0 

21.7 

41.9 

44.2 

51.9 

54  6 

68 

69 

61.3 

29.6 

30.9 

28.5 

22.2 

42.6 

44.8 

52.7 

55.5 

69 

70 

62.2 

30.0 

31.3 

28.9 

22.6 

43  3 

45.5 

53  5 

56.3 

70 

71 

63.1 

30.5 

31.8 

29.4 

23.1 

43.9 

46.2 

54.3 

57.1 

71 

72 

64.0 

30.9 

32.3 

29.8 

23.5 

44.6 

46.9 

55.1 

58.0 

72 

73 

64.8 

31.4 

32  7 

30.3 

24.0 

45.2 

47.6 

55.9 

58.8 

73 

74 

65.7 

31.8 

33.2 

30.8 

24.5 

45.9 

48.3 

56.7 

59.6 

74 

75 

66.6 

32.2 

33.6 

31.2 

24.9 

46.6 

49.0 

57.5 

60.5 

75 

76 

67.5 

32.7 

34.1 

31.7 

25.4 

47.2 

49.7 

58.2 

61.3 

79 

77 

68.4 

33.1 

34.5 

32.1 

25.9 

47.9 

50.4 

59.0 

62.1 

77 

78 

69.3 

33.6 

35.0 

32.6 

26.3 

48.5 

51.1 

59.8 

63.0 

78 

79 

70.2 

34.0 

35.4 

33.1 

26.8 

49.2 

51.8 

60.6 

63.8 

79 

80 

71.1 

34.4 

35.9 

33.5 

27.3 

49.9 

52.5 

61.4 

64.6 

80 

81 

71.9 

34.9 

36.3 

34.0 

27.7 

50.5 

53.2 

62.2 

65  5 

81 

82 

72.8 

35.3 

36.8 

34.5 

28.2 

51.2 

53.9 

63.0 

66.3 

82 

83 

73.7 

35  8 

37.3 

34.9 

28.6 

51.8 

54.6 

63.8 

67.1 

83 

84 

74.6 

36.2 

37.7 

35.4 

29.1 

52.5 

55.3 

64.6 

68.0 

84 

85 

75.5 

36.7 

38.2 

35.8 

29.6 

53.1 

56.0 

65.4 

68.8 

85 

86 

76.4 

37.1 

38.6 

36.3 

30.0 

53.8 

56.6 

66.2 

69.7 

86 

87 

77.3 

37.5 

39.1 

36.8 

30.5 

54.5 

57.3 

67.0 

70.5 

87 

88 

78.2 

38.0 

39.5 

37.2 

31.0 

55.1 

58.0 

67.8 

71.3 

88 

79.1 

38.4 

40.0 

37.7 

31.4 

55.8 

58.7 

68.5 

72.2 

80 

90 

79.9 

38.9 

40.4 

38.2 

31.9 

56.4 

59.4 

69.3 

73.0 

90 

91 

80.8 

39.3 

40.9 

38.6 

32.4 

57.1 

60.1 

70.1 

73.8 

91 

92 

81.7 

39.8 

41.4 

39.1 

32.8 

57.8 

60.8 

70.9 

74.7 

92 

93 

82.6 

40  2 

41  8 

39.6 

33.3 

58.4 

61.5 

71.7 

75  5 

93 

94 

83.5 

40.6 

42.3 

40.0 

33.8 

59.1 

62.2 

72.5 

78.3 

94 

95 

84.4 

41.1 

42.7 

40.5 

34.2 

59.7 

62.9 

73.3 

77.2 

95 

96 

85.3 

41.5 

43.2 

41.0 

34.7 

60.4 

63.6 

74.1 

78.0 

96 

97 

86.2 

42.0 

43.7 

41.4 

35.2 

61.1 

64.3 

74.9 

78.8 

97 

98 

87.1 

42.4 

44.1 

41.9 

35.6 

61.7 

65.0 

75.7 

79.7 

98 

99 

87.9 

42.9 

44.6 

42.4 

36.1 

62.4 

65.7 

76.5 

80.5 

99 

100 

88.8 

43.3 

45.0 

42.8 

36.6 

63.0 

66.4 

77.3 

81.3 

100 

101 

89  7 

43.8 

45  5 

43.3 

37.0 

63.7 

67.1 

78.1 

82.2 

101 

102 

90.6 

44.2 

46.0 

43.8 

37.5 

64.4 

67.8 

78.8 

83.0 

102 

103 

91.5 

44.7 

46.4 

44.2 

38.0 

65.0 

68.5 

79.6 

83.8 

103 

104 

92.4 

45.1 

46.9 

44.7 

38.5 

65.7 

69.1 

80.4 

84.7 

104 

105 

93.3 

45.5 

47.3 

45.2 

38.9 

66.4 

69.8 

81.2 

85.5 

105 

106 

94.2 

46.0 

47.8 

45  6 

39.4 

67.0 

70.5 

82.0 

86.3 

106 

107 

95.0 

46.4 

48.3 

46.1 

39.9 

67.7 

71.2 

82.8 

87.2 

107 

108 

95.9 

46.9 

48.7 

46.6 

40.3 

68.3 

71.9 

83.6 

88.0 

108 

109 

96.8 

47.3 

49.2 

47.0 

40.8 

69.0 

72.6 

84.4 

88.8 

109 

110 

97.7 

47.8 

49.6 

47.5 

41.3 

69.7 

73.3 

85.2 

89.7 

110 

111 

98.6 

48.2 

50.1 

48.0 

41.7 

70.3 

74.0 

86.0 

90.5 

111 

112 

99.5 

48. 7 

50.6 

48.4 

42.2 

71.0 

74.7 

86.8 

91.3 

112 

113 

100.4 

49.1 

51.0 

48.9 

42.7 

71.6 

75.4 

87.6 

92.2 

113 

114 

101.3 

49.6 

51.5 

49.4 

43.2 

72.3 

76.1 

88.4 

93.0 

114 

115 

102.2 

50.0 

51.9 

49.8 

43.6 

73.0 

76.8 

89  2 

93  9 

115 

116 

103.0 

50.5 

52.4 

50.3 

44  1 

73.6 

77.5 

90  0 

94.7 

116 

117 

103  9 

50.9 

52.9 

50.8 

44.6 

74.3 

78.2 

90.7 

95.5 

117 

118 

104.8 

51.4 

53.3 

51.2 

45.0 

75.0 

78.9 

91.5 

96.4 

118 

119 

105.7 

51.8 

53.8 

51.7 

45.5 

79.6 

92.3 

97.2 

119 

90 
27 


METHODS    OF   ANALYSIS 

Table  1.— Munson  and  Walker's  Table.— Continued. 

[Expressed  in  milligrams.! 


[Chap. 


1 

6 

K 
B< 

8 

g 
o 

m 

a 

PS 

•<! 
0 

i 

INVERT  8U0AR 
AND  SUCROSE 

LACTOSE 

MALTOSE 

f 

9 

o 

0 

s 
g 

s 

o 

3 
s 

k 

1 

w 
6 

9 

W 
6 

1 

2 
O 

O 

1 

c3 

O 
o 

b 

0 
PS 

g 

120 

106.6 

52.3 

54.3 

52.2 

46.0 

76.3 

80.3 

93.1 

98.0 

120 

121 

107.5 

64.7 

52.7 

46.6 

76.9 

81.0 

93.9 

98.9 

121 

122 

108.4 

63]  2 

55.2 

63.1 

46.9 

77.6 

81.7 

94.7 

99.7 

122 

123 

109.3 

53.6 

55.7 

63.6 

47.4 

78.3 

82.4 

95.5 

100.6 

123 

124 

110.1 

54.1 

66.1 

64.1 

47.9 

78.9 

83.1 

96.3 

101.4 

124 

125 

111.0 

54.5 

66.6 

64.5 

48.3 

79.6 

83.8 

97.1 

102.2 

125 

126 

111.9 

55.0 

57.0 

55.0 

48.8 

80.3 

84,5 

97.9 

103.0 

126 

127 

112.8 

55.4 

57.5 

65.5 

49.3 

80.9 

85.2 

98.7 

103.9 

127 

128 

113.7 

55.9 

58.0 

55.9 

49.8 

81.6 

85.9 

99.4 

104.7 

128 

129 

114.6 

66.3 

58.4 

66.4 

50.2 

82.2 

86.6 

100.2 

105.5 

129 

130 

115.5 

56.8 

58.9 

66.9 

60.7 

82.9 

87.3 

101.0 

108.4 

130 

131 

116.4 

57.2 

59.4 

57.4 

51.2 

83.6 

88.0 

101.8 

107.2 

131 

132 

117.3 

57.7 

59.8 

67.8 

51.7 

84.2 

88  7 

102.6 

108,0 

132 

133 

118.1 

58.1 

60.3 

58.3 

52.1 

84.9 

89.4 

103,4 

108,9 

133 

134 

119.0 

58.6 

60.8 

58.8 

52.6 

85.5 

90.1 

104.2 

109.7 

134 

135 

119.9 

59.0 

61.2 

59.3 

53.1 

86.2 

90.8 

105,0 

110,5 

135 

136 

120.8 

69.5 

61.7 

69.7 

53.6 

86.9 

91.5 

105.8 

111.4 

136 

137 

121.7 

60.0 

62.2 

60.2 

64.0 

87.6 

92.1 

106.6 

112,2 

137 

138 

122.6 

60.4 

62.6 

60.7 

64.5 

88.2 

92.8 

107.4 

113.0 

138 

139 

123.5 

60.9 

63.1 

61.2 

65.0 

88.9 

93.6 

108.2 

113.9 

139 

140 

124.4 

61.3 

63.6 

61.6 

66.5 

89.5 

94.2 

109.0 

114,7 

140 

141 

125.2 

61.8 

64.0 

62.1 

55.9 

90.2 

94.9 

109.8 

115.6 

141 

142 

126.1 

62.2 

64.5 

62,6 

56.4 

90.8 

95.6 

110.5 

116.4 

143 

143 

127.0 

62.7 

65.0 

63.1 

56.9 

91.6 

96.3 

111.3 

117.2 

143 

144 

127.9 

63.1 

65.4 

63.5 

57.4 

92.2 

97.0 

112.1 

118.0 

144 

145 

128.8 

63.6 

65.9 

64.0 

67.8 

92.8 

97.7 

112.9 

118.9 

146 

146 

129.7 

64.0 

66.4 

64.5 

58.3 

93.5 

98.4 

113.7 

119.7 

146 

147 

130.6 

64.5 

66.9 

65.0 

58.8 

94.2 

99.1 

114,5 

120,5 

147 

148 

131.5 

65.0 

67.3 

65.4 

69.3 

94.8 

99.8 

115.3 

121.4 

148 

149 

132.4 

65.4 

67.8 

65.9 

69.7 

95.5 

100.5 

116.1 

122.2 

149 

150 

133.2 

65.9 

68.3 

66.4 

60.2 

96.1 

101.2 

116.9 

123.0 

150 

151 

134.1 

66.3 

68.7 

66.9 

60.7 

96.8 

101.9 

117.7 

123.9 

151 

152 

135.0 

66.8 

69.2 

67.3 

61.2 

97.5 

102,6 

118.5 

124.7 

152 

153 

135.9 

67.2 

69.7 

67.8 

61.7 

98.1 

103.3 

119,3 

125.6 

153 

164 

136.8 

67.7 

70.1 

68.3 

62.1 

98.8 

104.0 

120.0 

126.4 

154 

155 

137.7 

68.2 

70.6 

68.8 

62.6 

99.5 

104.7 

120.8 

127.2 

155 

156 

138.6 

68.6 

71.1 

69.2 

63.1 

100.1 

105.4 

121.6 

128.0 

156 

157 

139.5 

69.1 

71.6 

63.6 

100.8 

106.1 

122.4 

128.9 

157 

158 

140.3 

69.5 

72.0 

70!2 

64.1 

101.6 

106.8 

123.2 

129.7 

158 

159 

141.2 

70.0 

72.5 

70.7 

64.6 

102.1 

107.5 

124.0 

130.6 

159 

160 

142.1 

70.4 

73.0 

71.2 

65.0 

102.8 

108.2 

124.8 

131.4 

160 

161 

143.0 

70.9 

73.4 

71.6 

65.5 

103,4 

108,9 

125.6 

132.2 

161 

162 

143.9 

71.4 

73.9 

72.1 

66.0 

104.1 

109.6 

126,4 

133.0 

162 

163 

144,8 

71.8 

74.4 

72.6 

66,5 

104.8 

110.3 

127.2 

133,9 

163 

164 

145.7 

72.3 

74.9 

73.1 

66.9 

106.4 

111.0 

128.0 

134,7 

164 

165 

146.6 

72.8 

75.3 

73.6 

67.4 

106.1 

111.7 

128.8 

135,5 

165 

166 

147.5 

73.2 

75.8 

74.0 

67.9 

106.8 

112.4 

129.6 

136,4 

166 

167 

148.3 

73.7 

76.3 

"4.6 

68.4 

107.4 

113.1 

130.3 

137.2 

167 

168 

149.2 

74.1 

76.8 

75.0 

68.9 

108.1 

113.8 

131.1 

138.0 

168 

169 

150.1 

74.6 

77.2 

76.5 

69.3 

108.8 

114.5 

131.9 

138.9 

169 

170 

151.0 

75.1 

77.7 

76.0 

69.8 

109.4 

115.2 

132.7 

139.7 

170 

171 

151.9 

75.5 

78.2 

76.4 

70.3 

110.1 

115.9 

133,5 

140.5 

171 

172 

152.8 

76.0 

78.7 

76.9 

70.8 

110.8 

116.6 

134,3 

141.4 

172 

173 

153.7 

76.4 

79.1 

77.4 

71.3 

111.4 

117.3 

135.1 

142,2 

173 

174 

154.6 

76.9 

79.6 

77.9 

71.7 

112.1 

118.0 

135.9 

143.0 

174 

vnii 

27 


Table  1.- 


FOODS   AND    FEEDING    STUFFS 


-MUNSON  AND  WALKER'S  TABLE. 
(Expressed  in  milligrams.! 


91 


-Continued. 


1 

§ 

INVERT  SUGAR 
AND  SUCROSE 

LACTOSE 

MALTOSE 

3 

o 

o 

a 
6 

o 

a 
■< 
o 

D 

"5 
3 

1 

9 

§ 

a 
o 

g 

1 

<0 

E 
2  *- 

iu 

6 

1 

6 

6 

6 

g 

1 

3 

a 

o 

^ 

4 

o 

6 

o 

175 

155.5 

77  4 

80  I 

78.4 

72.2 

112.8 

118.7 

136.7 

143.9 

175 

176 

1.56.3 

77  8 

80  6 

78  8 

72.7 

113.4 

119.4 

137.5 

144  7 

176 

177 

1.57.2 

78  3 

81  0 

79  3 

73  2 

114.1 

120  1 

138.3 

145.5 

177 

178 

1.58  1 

78  8 

81  5 

798 

73.7 

114.8 

120.8 

139.1 

146.4 

178 

179 

159.0 

79.2 

82.0 

80.3 

74.2 

115.4 

121.5 

139.8 

147.2 

179 

180 

1.59  9 

79  7 

82  5 

80.8 

74.6 

116.1 

122.2 

140.6 

148.0 

180 

181 

160.8 

80.1 

82.9 

81  3 

75.1 

116.7 

122.9 

141  4 

148.9 

181 

182 

lfil.7 

80  6 

83.4 

81  7 

75.6 

117.4 

123.6 

142.2 

140.7 

182 

183 

162.6 

81  1 

83  9 

82  2 

76  1 

118.1 

124.3 

143.0 

150.5 

183 

184 

163.4 

81.5 

84.4 

82.7 

76.6 

118.7 

125.0 

143.8 

151.4 

184 

185 

164.3 

82  0 

84.9 

83.2 

77.1 

119.4 

125.7 

144.6 

1.52.2 

185 

186 

165  2 

82.5 

85.3 

83.7 

77.6 

120.1 

126.4 

145.4 

153.0 

188 

187 

166  1 

82.9 

85  8 

84  2 

78  0 

120.7 

127.1 

146  2 

1.53  9 

187 

188 

167  0 

83  4 

86  3 

84.6 

78.5 

121.4 

127.8 

147.0 

154.7 

188 

189 

167.9 

83.9 

86.8 

85.1 

79.0 

122.1 

128.5 

147.8 

155.5 

189 

100 

168  8 

84.3 

87.2 

85.6 

79.5 

122.7 

120.2 

148.6 

156.4 

190 

101 

160  7 

84  8 

87  7 

86.1 

80.0 

123.4 

129.9 

149.3 

157.2 

101 

102 

170  5 

85  3 

88.2 

86.6 

80.5 

124.1 

130.6 

1.50.1 

1.58.0 

192 

103 

171.4 

85  7 

88  7 

87.1 

81.0 

121.7 

131.3 

150.9 

158.9 

193 

194 

172.3 

86.2 

89.2 

87.6 

81.4 

125.4 

132.0 

151.7 

159.7 

194 

105 

173  2 

86.7 

89.6 

88.0 

81.9 

126.1 

132.7 

1.52.5 

160.5 

195 

106 

174  1 

87.1 

90  1 

88.5 

82.4 

126.7 

133.4 

1,53.3 

161.4 

106 

107 

175  0 

87  6 

90.6 

80  0 

82.9 

127  4 

134.1 

1.54.1 

162  2 

197 

108 

175  9 

88  1 

91  1 

89.5 

83.4 

128  1 

134.8 

154.9 

163.0 

198 

199 

176.8 

88.5 

91.6 

90.0 

83.9 

128.7 

135.5 

155.7 

163.9 

199 

200 

177  7 

89  0 

92.0 

90.5 

84.4 

120.4 

136.2 

156.5 

164.7 

200 

201 

178  5 

89  5 

92  5 

91.0 

84.8 

130.0 

1.36.9 

157.3 

165.5 

201 

202 

179  4 

89  9 

93  0 

91  4 

85.3 

130.7 

137.6 

158.1 

166.4 

202 

203 

180.3 

90  4 

93.5 

91.9 

85.8 

131.4 

138.3 

158.8 

167.2 

203 

204 

181.2 

90.9 

94.0 

92.4 

86.3 

132.0 

139.0 

159.6 

168.0 

204 

205 

182  1 

91.4 

94.5 

92.9 

86.8 

132.7 

139.7 

160.4 

168.9 

205 

206 

183  0 

91  8 

94.9 

93.4 

87.3 

133.4 

140  4 

161.2 

ir,9.7 

206 

207 

183.9 

92  3 

95.4 

93.9 

87.8 

1.34.0 

141.1 

162.0 

170  5 

207 

208 

184  8 

92  8 

95.9 

94.4 

88.3 

1.34.7 

141.8 

162.8 

171.4 

208 

209 

185.6 

93.2 

96.4 

94.9 

88.8 

135.4 

142.5 

163.6 

172.2 

209 

210 

186  5 

93.7 

96.9 

95.4 

89.2 

1.36  0 

143.2 

164.4 

173.0 

210 

211 

187  4 

94.2 

97.4 

95.8 

89.7 

136  7 

143.9 

165.2 

173.8 

211 

212 

188  3 

94.6 

97.8 

96.3 

90  2 

137  4 

144.6 

166.0 

174.7 

212 

213 

189  2 

95  1 

98.3 

96.8 

90.7 

138.0 

145.3 

166.8 

175.5 

213 

214 

190.1 

95.6 

98.8 

97.3 

91.2 

138.7 

146.0 

167.5 

176.4 

214 

215 

191  0 

96  1 

99  3 

97.8 

91.7 

139.4 

146.7 

168  3 

177.2 

215 

216 

191  9 

96.5 

99  8 

98.3 

92.2 

140  0 

147.4 

160.1 

178.0 

216 

217 

102  8 

97.0 

100  3 

98.8 

92.7 

140.7 

148.1 

169.9 

178.9 

217 

218 

103  6 

97.5 

100.8 

99  3 

93.2 

141.4 

148.8 

170.7 

179.7 

218 

219 

194.5 

98.0 

101.2 

99.8 

93.7 

142.0 

149.5 

171.5 

180.5 

219 

220 

195  4 

98  4 

101.7 

100.3 

94.2 

142.7 

150.2 

172.3 

181.4 

220 

221 

196  3 

98  9 

102  2 

100  8 

94.7 

143  4 

150.9 

173  1 

182.2 

221 

222 

197  2 

99  4 

102.7 

101.2 

95  1 

144  0 

151.6 

173.9 

183  0 

222 

223 

108  1 

99  9 

103.2 

101.7 

95  6 

144.7 

152.3 

174.7 

183.9 

223 

224 

199.0 

100.3 

103.7 

102.2 

96.1 

145.4 

153.0 

175.5 

184.7 

224 

225 

109.9 

100.8 

104.2 

102.7 

96.6 

146  0 

153.7 

176.2 

185.5 

225 

226 

200  7 

101.3 

IM  6 

103.2 

97.1 

146.7 

154.4 

177.0 

186.4 

228 

227 

201  6 

101  8 

105  1 

103  7 

97.6 

147.4 

155  1 

177.8 

187  2 

227 

228 

202.5 

102.2 

105  6 

104.2 

98  1 

148.0 

1.55  8 

178.6 

188.0 

228 

229 

203.4 

102.7 

106.1 

104.7 

98.6 

148.7 

156.5 

179.4 

188.8 

229 

92 
27 


METHODS    OF   ANALYSIS 


Table  1. — Munson  and  Wali-oer'S  Table. 

lExpressed  in  milligrams.) 


[Chap. 


-Continued. 


3 

8 
p 

INVERT  SUGAR 
AND  SUCROSE 

LACTOSE 

MAITOSE 

3 

o 

o 

"3 

"3 

a 
o 

w 

s 

s: 

p 

s 

a 

1 

q 

1 

q 

6 

O 

w 

6 

0 

g 

1 

o 

03  ^„ 
&3 

5! 

CJ 

i 

6 

Si 

6 

1 

230 

204.3 

103.2 

106.6 

105.2 

99,1 

149.4 

157.2 

180.2 

189.7 

230 

231 

205.2 

103.7 

107.1 

105.7 

99.6 

150.0 

157,9 

181.0 

190.5 

231 

232 

206.1 

104.1 

107.6 

106.2 

100.1 

150.7 

158.6 

181.8 

191.3 

232 

233 

207.0 

104.6 

108.1 

106,7 

100.6 

151,4 

159.3 

182.6 

192.2 

233 

234 

207.9 

105.1 

108.6 

107.2 

101.1 

152.0 

160,0 

183.4 

193.0 

234 

235 

208.7 

105.6 

109,1 

107,7 

101.6 

152,7 

160,7 

184.2 

193.8 

235 

236 

209,6 

106.0 

109.5 

108,2 

102.1 

153.4 

161.4 

184.9 

194,7 

238 

237 

210.5 

106.5 

110.0 

108.7 

102,6 

154.0 

162.1 

185.7 

195,5 

237 

238 

211.4 

107.0 

110.5 

109,2 

103,1 

154,7 

162.8 

186.5 

196.3 

238 

239 

212.3 

107.5 

111.0 

109,6 

103,5 

155,4 

163.5 

187,3 

197.2 

239 

240 

213.2 

108.0 

111.5 

110,1 

104,0 

156,1 

164.3 

188.1 

198.0 

240 

241 

214.1 

108.4 

112,0 

110,6 

104.5 

156,7 

165.0 

188.9 

198.8 

241 

242 

215.0 

108.9 

112,5 

111.1 

105,0 

157.4 

165.7 

199,7 

242 

243 

215.8 

109.4 

113.0 

111,6 

105,5 

158,1 

166.4 

190^5 

200,5 

243 

244 

216.7 

109.9 

113.5 

112,1 

106,0 

158.7 

167.1 

191,3 

201.3 

244 

245 

217.6 

110  4 

114.0 

112.6 

106.5 

159.4 

167.8 

192.1 

202.2 

245 

246 

21S.5 

110.8 

114.5 

113.1 

107.0 

160.1 

168.5 

192.9 

203.0 

246 

247 

219.4 

111.3 

115.0 

113,6 

107.5 

160.7 

169.2 

193.6 

203.8 

247 

248 

220.3 

111.8 

115.4 

114,1 

103,0 

161.4 

189.9 

194.4 

204.7 

248 

249 

221.2 

112.3 

115.9 

114.6 

108.5 

162.1 

170.6 

195,2 

205,5 

249 

250 

222.1 

112.8 

116.4 

115.1 

109,0 

162.7 

171.3 

196.0 

206.3 

250 

251 

223.0 

113.2 

116.9 

115,6 

109.5 

153,4 

172.0 

196.8 

207.2 

251 

252 

223.8 

113.7 

117.4 

116.1 

110.0 

164  1 

172.7 

197.6 

208.0 

252 

253 

224.7 

114.2 

117.9 

116.6 

110.5 

164.7 

173.4 

198.4 

208.8 

253 

254 

225.6 

114.7 

118.4 

117.1 

111.0 

165,4 

174.1 

199,2 

209,7 

254 

255 

226.5 

115.2 

118,9 

117.6 

111,5 

166.1 

174,8 

200,0 

210,5 

255 

256 

227.4 

115.7 

119,4 

118,1 

112.0 

166,8 

175,5 

200,8 

211,3 

256 

257 

228.3 

116.1 

119.9 

118,6 

112.5 

167,4 

176.2 

201,6 

212,2 

257 

258 

229.2 

116.6 

120,4 

119.1 

113,0 

168.1 

176,9 

202,3 

213.0 

258 

259 

230.1 

117.1 

120.9 

119.6 

113.5 

168.8 

177.6 

203.1 

213.8 

259 

260 

231.0 

117.6 

121,4 

120,1 

114,0 

169,4 

178.3 

203.9 

214,7 

260 

261 

231.8 

118.1 

121,9 

120,6 

114.5 

170.1 

179  0 

204.7 

215,5 

261 

262 

232.7 

118.6 

122,4 

121.1 

115.0 

170.8 

179.8 

205.5 

216.3 

262 

263 

233.6 

119.0 

122,9 

121.6 

115.5 

171.4 

180.5 

206.3 

217.2 

263 

264 

234.5 

119.5 

123.4 

122,1 

116.0 

172,1 

181.2 

207,1 

218,0 

264 

265 

235.4 

120.0 

123.9 

122,6 

116.5 

172.8 

181.9 

207,9 

218.8 

265 

266 

236.3 

120.5 

124,4 

123,1 

117.0 

173,5 

182,6 

208,7 

219,7 

266 

267 

237.2 

121.0 

124,9 

123,6 

117.5 

174.1 

183.3 

209,5 

220,5 

267 

268 

238.1 

121.5 

125.4 

124.1 

118.0 

174.8 

184.0 

210,3 

221,3 

268 

269 

238.9 

122.0 

125,9 

124.6 

118.5 

175.5 

184.7 

211.0 

222,1 

269 

270 

239.8 

122.5 

126.4 

125,1 

119.0 

176. 1 

185.4 

211.8 

223,0 

270 

271 

240.7 

122.9 

126.9 

125.6 

119,5 

176.8 

186.1 

212.6 

223.8 

271 

272 

241.6 

123.4 

127,4 

126.2 

120,0 

177.5 

213.4 

224.6 

272 

273 

242.5 

123.9 

127,9 

126.7 

120.6 

178.1 

187^5 

214.2 

225  5 

273 

274 

243.4 

124.4 

128.4 

127,2 

121,1 

178,8 

188,2 

215.0 

226.3 

274 

275 

244.3 

124.9 

128,9 

127.7 

121,6 

179,5 

188,9 

215.8 

227.1 

275 

276 

245.2 

125.4 

129.4 

128.2 

122.1 

180,2 

189.6 

216.6 

228.0 

276 

277 

246.1 

125.9 

129.9 

•    128.7 

122.6 

180  8 

190.3 

217.4 

228  8 

277 

278 

246.9 

126.4 

130.4 

129,2 

123.1 

181  5 

191.0 

218.2 

229.6 

278 

279 

247.8 

126.9 

130,9 

129,7 

123,6 

182.2 

191,7 

218.9 

230.5 

279 

280 

248.7 

127.3 

131.4 

130,2 

124.1 

182.8 

192,4 

219.7 

231.3 

280 

281 

249.6 

127.8 

131  9 

130,7 

124,6 

183.5 

193  1 

220.5 

232  1 

281 

282 

250.5 

128.3 

132.4 

131,2 

125,1 

184.2 

193.9 

221.3 

233  0 

282 

283 

251.4 

128.8 

132,9 

131,7 

125.6 

184,8 

194.6 

222.1 

233.8 

283 

284 

252.3 

129,3 

133.4 

132.2 

126.1 

185,5 

195.3 

222.9 

234.6 

284 

vni] 

27 


FOODS  AND  FEEDING  STUFFS 


Table  1.— ISIunson  and  WalivER's  Table. 

[Expressed  in  milligrams.] 


93 


-Continued. 


1 

INVEST  SUG.VR 
AND  8UCR  8E 

LACTOSE 

MALTOSE 

9. 

3 

O 

o 

>j 

_ 

0 

o 

1 

2 

i 

3 

1 

9 

a 

8 

s 

§ 

i. 

iu 

o 

6 

8 

6 

00 

s 

I 

a 

Ui  u 

M  3 

i 

a 

s 

o 

B 

o 

Q 

2 

2" 

c." 

6 

6 

d 

o 

& 

285 

253.2 

129.8 

133.9 

1,32.7 

126.6 

186.2 

196.0 

223.7 

235.5 

285 

286 

254.0 

130.3 

134.4 

133.2 

127.1 

186.9 

196.7 

224.5 

2.36.3 

286 

287 

254.9 

130.8 

134.9 

133.7 

127.6 

187.5 

197.4 

225.3 

237.1 

287 

288 

255.8 

131.3 

135.4 

134.3 

128.1 

188.2 

198.1 

226.1 

238.0 

288 

289 

256.7 

131.8 

135.9 

134.8 

128.6 

188.9 

198.8 

226.9 

238.8 

289 

290 

257.6 

132.3 

136.4 

135.3 

129.2 

189.5 

199.5 

227.6 

239.6 

290 

291 

258.5 

132.7 

136.9 

135.8 

129.7 

190.2 

200.2 

228.4 

240.5 

291 

392 

259.4 

133.2 

137.4 

136  3 

130.2 

190.9 

200.9 

229.2 

241.3 

292 

293 

260.3 

133.7 

137.9 

136.8 

130.7 

191.5 

201.6 

230.0 

242.1 

293 

294 

261.2 

134.2 

138.4 

137.3 

131.2 

192.2 

202.3 

230.8 

242.9 

294 

295 

262.0 

134.7 

138.9 

137.8 

1.31.7 

192.9 

203.0 

231.6 

243.8 

295 

296 

262.9 

135.2 

139.4 

138.3 

1.32.2 

193.6 

203.7 

232.4 

244.6 

296 

297 

263.8 

135.7 

140.0 

13S.8 

132.7 

194.2 

204.4 

233.2 

245.4 

297 

298 

264.7 

136.2 

140.5 

139.4 

133.2 

194.9 

205.1 

234.0 

246.3 

298 

299 

265.6 

136.7 

141.0 

139.9 

133.7 

195.6 

205.8 

234.8 

247.1 

299 

300 

266.5 

137  2 

141.5 

140.4 

134.2 

196.2 

206.6 

235.5 

247.9 

300 

301 

267.4 

137.7 

142.0 

140.9 

134.8 

196.9 

207.3 

236.3 

248.8 

301 

302 

268.3 

138.2 

142.5 

141.4 

135.3 

197.6 

208.0 

237.1 

249.6 

302 

303 

269.1 

138.7 

143.0 

141.9 

135.8 

198.3 

208.7 

237.9 

250.4 

303 

304 

270.0 

139.2 

143.5 

142.4 

136.3 

198.9 

209.4 

238.7 

251.3 

304 

305 

270.9 

139.7 

144.0 

142.9 

136.8 

199.6 

210.1 

239.5 

252.1 

305 

306 

271.8 

140.2 

144.5 

143.4 

137.3 

200.3 

210.8 

240.3 

252.9 

306 

307 

272.7 

140.7 

145.0 

144.0 

137.8 

201.0 

211.5 

241.1 

2.53.8 

307 

308 

273.6 

141.2 

145.5 

144.5 

138.3 

201.6 

212.2 

241.9 

254.6 

308 

309 

274.5 

141.7 

146.1 

145.0 

138.8 

202.3 

212.9 

242.7 

255.4 

309 

310 

275.4 

142.2 

146.6 

145.5 

139.4 

203.0 

213.7 

243.5 

256.3 

310 

311 

276.3 

142.7 

147.1 

146.0 

139.9 

203.6 

214.4 

244.2 

257.1 

311 

312 

277.1 

143.2 

147.6 

146.5 

140.4 

204.3 

215.1 

245.0 

257.9 

312 

313 

278.0 

143.7 

148.1 

147.0 

140.9 

205.0 

215.8 

245.8 

258.8 

313 

314 

278.9 

144.2 

148.6 

147.6 

141.4 

205.7 

216.5 

246.6 

259.6 

314 

315 

279.8 

144.7 

149.1 

148.1 

141.9 

206.3 

217.2 

217.4 

260.4 

315 

316 

280.7 

145.2 

149.6 

148.6 

142  4 

207.0 

217.9 

248.2 

261.2 

316 

317 

281.6 

145.7 

150.1 

149.1 

143.0 

207.7 

218.6 

249.0 

262.1 

317 

3ia 

282.5 

146.2 

150.7 

149.6 

143.5 

208.4 

219.3 

249.8 

262.9 

318 

319 

283.4 

146.7 

151.2 

150.1 

144.0 

209.0 

220.0 

250.6 

263.7 

319 

320 

284.2 

147.2 

151.7 

150.7 

144.5 

209.7 

220.7 

2.51.3 

264.6 

320 

321 

285.1 

147.7 

152.2 

151.2 

145.0 

210.4 

221.4 

2.52.1 

265.4 

321 

322 

286.0 

148.2 

152.7 

151.7 

145.5 

211.0 

222.2 

252.9 

266.2 

322 

323 

286.9 

148.7 

153.2 

152.2 

146.0 

211.7 

222.9 

253.7 

267.1 

323 

324 

287.8 

149.2 

153.7 

152.7 

146.6 

212.4 

223.6 

254.5 

267.9 

324 

325 

288.7 

149.7 

154.3 

153.2 

147.1 

213.1 

224.3 

255.3 

268.7 

325 

326 

289.6 

150.2 

1.54.8 

153.8 

147.6 

213.7 

225.0 

256.1 

269.6 

326 

327 

290.5 

150.7 

1.55.3 

154.3 

148.1 

214.4 

225.7 

256.9 

270.4 

327 

328 

291.4 

151.2 

155.8 

154.8 

148.6 

215.1 

226.4 

257.7 

271.2 

328 

329 

292.2 

151.7 

156.3 

155.3 

149.1 

215.8 

227.1 

258.5 

272.1 

329 

330 

293.1 

152.2 

156.8 

155.8 

149.7 

216.4 

227.8 

259.3 

272.9 

330 

331 

294.0 

1.52.7 

157.3 

156.4 

150  2 

217.1 

228.5 

260.0 

273.7 

331 

332 

294.9 

153.2 

157.9 

1.56.9 

150.7 

217.8 

229.2 

260.8 

274.6 

332 

333 

295.8 

153.7 

158  4 

157.4 

151.2 

218.4 

230.0 

261  6 

275  4 

333 

334 

296.7 

154.2 

158.9 

157.9 

151.7 

219.1 

230.7 

262.4 

276.2 

334 

335 

297.6 

154.7 

159.4 

158.4 

152.3 

219.8 

231.4 

263.2 

277.0 

335 

336 

208.5 

155.2 

159.9 

159.0 

152.8 

220.5 

232.1 

264  0 

277.9 

336 

337 

299.3 

155.8 

160.5 

1.59  5 

153.3 

221.1 

232.8 

264.8 

278.7 

337 

338 

300.2 

156.3 

161.0 

160.0 

153.8 

221.8 

233.5 

265.6 

279.5 

338 

339 

301.1 

156.8 

161.5 

160.5 

154.3 

222.5 

234.2 

266.4 

280.4 

339 

94 
27 


METHODS    OF   ANALYSIS 


Table  1.— Munson  and  Walker-s  Table.- 

(Expressed  in  milligrams.] 


[Chap. 


-Continued. 


f 

1 

INVERT  8(;OAR 
AND  8LCR09B 

LACTOSE 

UAI-TOaE 

3 

o 

_ 

O 

>j 

le 

a 

0 

s 
s 

1 

"a 

u 

e 
g 

8 

1 

i 

■< 
O 

a 

S 

> 

2 

o 

h 

o 

O 
?: 

6 

K 

6 

1 

j 

340 

302.0 

157.3 

162.0 

161.0 

154.8 

223.2 

234.9 

267.1 

281.2 

340 

341 

302.9 

157.8 

162.5 

161.6 

155.4 

223.8 

235.6 

267.9 

282.0 

341 

342 

303.8 

158.3 

163.1 

162.1 

155.9 

224.5 

236,3 

268.7 

282.9 

342 

343 

304.7 

158.8 

163.6 

162.6 

156.4 

225.2 

237,0 

269.5 

283.7 

343 

344 

305.6 

159.3 

164.1 

163.1 

156.9 

225,9 

237.8 

270.3 

284.5 

344 

345 

306.5 

159.8 

164.6 

163.7 

157.5 

226,5 

238.5 

271.1 

285.4 

345 

346 

307.3 

160.3 

165.1 

164.2 

158.0 

227,2 

239.2 

271.9 

286  2 

340 

347 

308.2 

160.8 

165,7 

164.7 

158.5 

227,9 

239.9 

272.7 

2.87.0 

347 

348 

309.1 

161.4 

166.2 

165.2 

159.0 

228,5 

240.6 

273.5 

287.9 

348 

349 

310.0 

161.9 

166.7 

165.7 

159.5 

229.2 

241.3 

274.3 

288.7 

349 

350 

310.9 

162  4 

167.2 

166.3 

160.1 

229.9 

242.0 

275.0 

289.5 

350 

351 

311.8 

162.9 

167.7 

166.8 

160.6 

230.6 

242,7 

275.8 

290  4 

351 

352 

312.7 

163.4 

168.3 

167.3 

161.1 

231.2 

243,4 

276.6 

291.2 

352 

353 

313.6 

163  9 

168.8 

167.8 

161.6 

231.9 

244,1 

277.4 

292.0 

353 

354 

314.4 

164.4 

169.3 

168.4 

162.2 

232.6 

244.8 

278.2 

292.8 

354 

355 

315.3 

164.9 

169.8 

168.9 

162.7 

233.3 

245.6 

279.0 

293.7 

355 

356 

316.2 

165.4 

170.4 

169.4 

163.2 

233.9 

246.3 

279.8 

294.5 

358 

357 

317.1 

166  0 

170.9 

170,0 

163.7 

234.6 

247.0 

280.6 

295.3 

357 

358 

318. 0 

166.5 

171.4 

170.5 

164.3 

235.3 

247.7 

281.4 

296  2 

358 

359 

318.9 

167.0 

171.9 

171.0 

164.8 

236.0 

248.4 

282.2 

297.0 

359 

360 

319.8 

167.5 

172.5 

171.5 

165,3 

236.7 

249.1 

282.9 

297.8 

360 

361 

320.7 

168.0 

173.0 

172.1 

165.8 

237.3 

249.8 

283.7 

298.7 

381 

362 

321.0 

168.5 

173.5 

172.6 

166.4 

238.0 

250.5 

284.5 

299.5 

382 

363 

322.4 

169  0 

174.0 

173.1 

166.9 

238.7 

251.2 

285.3 

300.3 

363 

364 

323.3 

169.6 

174.6 

173.7 

167.4 

239.4 

252.0 

286.1 

301.2 

384 

365 

324.2 

170.1 

175.1 

174.2 

167.9 

240.0 

252.7 

286.9 

302.0 

365 

366 

325.1 

170.6 

175.6 

174.7 

168.5 

240.7 

253.4 

287.7 

302.8 

368 

367 

326.0 

171.1 

176.1 

175.2 

169.0 

241.4 

254.1 

288.5 

303.6 

367 

368 

326.9 

171.6 

176.7 

175.8 

169.5 

242.1 

254.8 

289.3 

304.5 

368 

369 

327.8 

172.1 

177.2 

176.3 

170.0 

242.7 

255.5 

290.0 

305.3 

369 

370 

328.7 

172.7 

177.7 

176.8 

170.6 

243.4 

256,2 

290.8 

306.1 

370 

371 

329.5 

173.2 

178.3 

177.4 

171.1 

244.1 

256,9 

291.6 

307  0 

371 

372 

330  4 

173.7 

178.8 

177.9 

171.6 

244.8 

257,7 

292.4 

307.8 

372 

373 

331.3 

174.2 

179.3 

178.4 

172.2 

245.4 

258.4 

293.2 

308.6 

373 

374 

332.2 

174.7 

179.8 

179.0 

172.7 

246.1 

259.1 

294.0 

309.5 

374 

375 

333.1 

175.3 

180  4 

179.5 

173.2 

246.8 

259.8 

294.8 

310.3 

375 

376 

334.0 

175.8 

180.9 

180.0 

173.7 

247.5 

260.5 

295.6 

311.1 

376 

377 

334.9 

176.3 

181.4 

180.6 

174.3 

248  1 

201.2 

296.4 

312.0 

377 

378 

335.8 

176.8 

182.0 

181.1 

174.8 

248.8 

261.9 

297.2 

312.8 

378 

379 

336.7 

177.3 

182.5 

181.6 

175.3 

249.5 

262.6 

297.9 

313.6 

379 

380 

3.37  5 

177.0 

183.0 

182.1 

175,9 

250.2 

263.4 

298,7 

314.5 

380 

381 

338  4 

178.4 

183.6 

182.7 

176,4 

250.8 

264.1 

299,5 

315.3 

381 

382 

339.3 

178  9 

184.1 

183.2 

176,9 

251.5 

264.8 

300,3 

316.1 

382 

383 

340  2 

179,4 

184.6 

183  8 

177,5 

252.2 

265.5 

301,1 

316.9 

383 

384 

341.1 

180.0 

185.2 

184.3 

178.0 

252.9 

266.2 

301,9 

317.8 

384 

385 

342.0 

180.5 

185.7 

184.8 

178.5 

253.6 

266.9 

302,7 

318.6 

385 

386 

342  9 

181.0 

186.2 

.  185.4 

179.1 

254.2 

267.6 

303,5 

319.4 

386 

387 

.343  8 

181.5 

186.8 

185.9 

179.6 

254.9 

268.3 

304.2 

320.3 

387 

388 

344.6 

182.0 

187.3 

186.4 

180.1 

255.6 

269.0 

305.0 

321.1 

388 

389 

345.5 

182.6 

187.8 

187.0 

180.6 

256.3 

269.8 

305.8 

321.9 

389 

390 

346.4 

183.1 

188.4 

187.5 

181.2 

256.9 

270.5 

306.6 

322.8 

390 

891 

347  3 

183.6 

188.9 

188.0 

181.7 

257.6 

271.2 

307.4 

323.6 

391 

392 

318  2 

184.1 

189  4 

188.8 

182.3 

258.3 

271.9 

308.2 

324.4 

392 

303 

340  1 

184.7 

190.0 

189.1 

182.8 

259.0 

272.0 

309.0 

325  2 

393 

394 

350.0 

185.2 

190.5 

189.7 

183.3 

259.6 

273.3 

309.8 

326.1 

394 

VIII] 
27 


FOODS  AND  FEEDING  STUFFS 


Table  1.— Munson  and  Walker-s  Table.— Continued. 

(Expressed  in  milligrams.) 


95 


1 

i 

INVERT  8UO.\R 
AND  SUCROSE 

LACTOSE 

MALTOSE 

5 

o 

_ 

0 

5 
2 

a 

_ 

? 

•< 

2 

q 

0 

a 

y, 
o 

o 

£ 

"5 

a 
§ 

g 
Q 

S 

k 

5 
to" 
o 

1 

0 

1 

0 

i 

6 

8 

§ 

g 
0 

395 

350.9 

185.7 

191.0 

190.2 

183.9 

260.3 

274.0 

310.6 

326.9 

395 

398 

351.8 

186.2 

191.6 

190.7 

184.4 

261.0 

274  7 

311.4 

327  7 

396 

397 

352.6 

186.8 

192  1 

191.3 

184.9 

261.7 

275.5 

312  1 

328.6 

397 

398 

353.5 

187.3 

192.7 

191  8 

185.5 

262.3 

276.2 

312.9 

329.4 

398 

399 

354.4 

187.8 

193.2 

192.3 

186.0 

263.0 

276.9 

313.7 

330.2 

399 

400 

355.3 

188.4 

193.7 

192.9 

186.5 

263.7 

277.6 

314.5 

331  1 

400 

401 

356.2 

188.9 

194.3 

193.4 

187.1 

264.4 

278.3 

315  3 

331.9 

401 

402 

357.1 

189.4 

194.8 

194.0 

187.6 

265.0 

279.0 

316.1 

332.7 

402 

403 

3.58.0 

189.9 

195.4 

194.5 

188.1 

265.7 

279  7 

31G.9 

333.6 

403 

404 

358.9 

190.5 

195.9 

195.0 

188.7 

266.4 

280.4 

317.7 

334.4 

404 

405 

.359.7 

191.0 

196.4 

195.6 

189.2 

267.1 

281.1 

318.5 

335  2 

405 

406 

360.6 

191.5 

197.0 

196.1 

189.8 

267  8 

281.9 

319.2 

.3.36  0 

408 

407 

.361.5 

192.1 

197.5 

196.7 

190.3 

268.4 

282.6 

320.0 

338  9 

407 

408 

362.4 

192.6 

198.1 

197.2 

190.8 

269  1 

283.3 

320.8 

337.7 

408 

409 

363.3 

193.1 

198.6 

197.7 

191.4 

269.8 

284.0 

321.6 

338.5 

409 

410 

364.2 

193.7 

199.1 

198.3 

191.9 

270.5 

284.7 

.322.4 

339.4 

410 

411 

365.1 

194  2 

199.7 

198.8 

192.5 

271.2 

285.4 

323  2 

340.2 

411 

412 

366.0 

194.7 

200.2 

199.4 

193.0 

286.2 

324.0 

341.0 

412 

413 

366.9 

195.2 

20O.S 

199.9 

193.5 

272:5 

286.9 

324.8 

341.9 

413 

414 

367.7 

195.8 

201.3 

200.5 

194.1 

273.2 

287.6 

325.6 

342.7 

414 

415 

368.6 

196.3 

201.8 

201.0 

194.6 

273.9 

288.3 

326.3 

343.5 

415 

416 

369.5 

196.8 

202.4 

201.6 

195.2 

274.6 

289.0 

327.1 

344.4 

416 

417 

370.4 

197.4 

202.9 

202.1 

195.7 

275.2 

289.7 

327.9 

345.2 

417 

418 

371.3 

197.9 

203.5 

202.6 

196.2 

275.9 

290.4 

328.7 

.346.0 

418 

419 

372.2 

198.4 

204.0 

203.2 

196.8 

276.6 

291.2 

329.5 

346.8 

419 

420 

373.1 

199.0 

204.6 

203.7 

197  3 

277  3 

291.9 

330.3 

347.7 

42Q 

421 

374.0 

199.5 

205.1 

204.3 

197.9 

277.9 

292.6 

331   1 

348.5 

421 

422 

374  8 

200.1 

205.7 

204.8 

198.4 

278.6 

293.3 

331.9 

349.3 

422 

423 

.375.7 

20T.6 

206.2 

205.4 

198.9 

279.3 

294.0 

3.32.7 

3.50.2 

423 

424 

376.6 

201.1 

206.7 

205.9 

199.5 

280.0 

294.7 

333.4 

351.0 

424 

425 

377.5 

201.7 

207.3 

206.5 

200.0 

280.7 

295.4 

334.2 

351.8 

425 

426 

378.4 

202.2 

207.8 

207.0 

200.6 

281.3 

296.2 

335.0 

352.7 

420 

427 

379.3 

202.8 

208.4 

207.6 

201.1 

282.0 

296.9 

3.35.8 

3,53.5 

427 

428 

380.2 

203.3 

208.9 

208.1 

201.7 

282.7 

297.6 

3,36  6 

354.3 

428 

429 

381.1 

203.8 

209.5 

208.7 

202.2 

283  4 

298.3 

337.4 

355.1 

429 

430 

382.0 

204.4 

210.0 

209.2 

202.7 

284.1 

299.0 

338.2 

356  0 

430 

431 

382.8 

204.9 

210.6 

209  8 

203.3 

284.7 

299.7 

339.0 

356.8 

431 

432 

383.7 

205.5 

211.1 

210.3 

203.8 

285.4 

300  5 

339.7 

357.6 

432 

433 

384.6 

206.0 

211.7 

210.9 

201.4 

286.1 

301.2 

340.5 

358.5 

433 

434 

385.5 

206.5 

212.2 

211.4 

204.9 

286.8 

301.9 

341.3 

359.3 

434 

435 

386.4 

207.1 

212.8 

212.0 

205.5 

287.5 

.302.6 

342.1 

360.1 

435 

436 

387.3 

207.6 

213.3 

212.5 

206.0 

288.1 

303.3 

342.9 

361.0 

436 

437 

388.2 

208.2 

213.9 

213.1 

205  6 

288.8 

304.0 

343.7 

361.8 

437 

438 

389  1 

208.7 

214.4 

213.6 

207.1 

289.5 

304.7 

344.5 

362  6 

438 

439 

390.0 

209.2 

215.0 

214.2 

207.7 

290.2 

305.5 

345  3 

363.4 

439 

440 

390.8 

209.8 

215.5 

214.7 

208.2 

290.9 

306.2 

346.1 

364  3 

440 

441 

391.7 

210.3 

216.1 

215.3 

203.8 

291.5 

306.9 

346.8 

365  1 

441 

442 

392.6 

210  9 

216.6 

215.8 

209.3 

292.2 

307.6 

347.6 

365  9 

442 

443 

393.5 

211.4 

217.2 

216.4 

209.9 

292.9 

308.3 

348.4 

366  8 

443 

444 

394.4 

212.0 

217.8 

216.9 

210.4 

293.6 

309.0 

349.2 

367  6 

444 

445 

395.3 

212.5 

218.3 

217.5 

211.0 

294.2 

309.7 

350.0 

,368.4 

445 

446 

396.2 

213.1 

218.9 

218  0 

211  5 

294  9 

310.5 

350.8 

369.3 

446 

447 

397.1 

213.6 

219.4 

218.6 

212.1 

295.6 

311  2 

351.6 

370  1 

447 

448 

397  9 

214  1 

220.0 

219  1 

212.6 

296.3 

311.9 

352.4 

370  9 

448 

449 

398.8 

214.7 

220.5 

219.7 

213.2 

297.0 

312.6 

353.2 

371.7 

449 

96 
27 


METHODS    OF   ANALYSIS 

Table    l.— Munson  and  Walker's  Table.- 

[Expressed  in  milligrams.) 


[Chap. 


-Continued. 


q 

i 

INVERT  SUGAR 
AND  SUCROSE 

LACTOSE 

MALTOSE 

0 

3 

o 

•a 

- 

9 

Q 
X 

C 

u 

1 

0 
0 

^ 

2 

0 

0 

0 
0 

m 

w 

s 

CD 

S 

p 

o 

H 

S  u 

e  i- 

0 

0 

0 

0 

0 

o 

0. 

1 

a 

1 

3 

03   C3 

u 

6 

6 

1 

6 

0 

K 

p 

450 

399.7 

215.2 

221  1 

220,2 

213.7 

297.6 

313.3 

353.9 

372.6 

450 

451 

400.6 

215.8 

221.6 

220,8 

214.3 

298.3 

314,0 

354,7 

373.4 

451 

452 

401.5 

216.3 

222.2 

221.4 

214,8 

299.0 

314,7 

355,5 

374.2 

452 

453 

402,4 

216.9 

222.8 

221,9 

215,4 

299,7 

315,5 

356,3 

375.1 

453 

454 

403.3 

217.4 

223.3 

222.5 

215.9 

300.4 

316.2 

357.1 

375.9 

454 

455 

404.2 

218.0 

223,9 

223,0 

216.5 

301,1 

316.9 

357.9 

376.7 

455 

456 

405.1 

218,5 

224  4 

223,6 

217.0 

301,7 

317.6 

358.7 

377.6 

456 

457 

405.9 

219,1 

225,0 

224,1 

217.6 

302.4 

318.3 

359.5 

378.4 

457 

458 

406.8 

219.6 

225.5 

224.7 

218.1 

303.1 

319.0 

360.3 

379.2 

458 

459 

407.7 

220.2 

226.1 

225.3 

218.7 

303.8 

319.8 

361.0 

380.0 

459 

460 

408,6 

220.7 

226.7 

225.8 

219.2 

304.5 

320.5 

361.8 

380.9 

460 

461 

409,5 

221.3 

227.2 

226.4 

219.8 

305.1 

321.2 

362.6 

381,7 

461 

462 

410,4 

221.8 

227.8 

226.9 

220.3 

305.8 

321.9 

363.4 

382  5 

462 

463 

411,3 

222.4 

228.3 

227.5 

220.9 

306,5 

322.6 

364.2 

383.4 

463 

464 

412,2 

222.9 

228.9 

228.1 

221.4 

307,2 

323.4 

365.0 

384.2 

464 

465 

413,0 

223.5 

229.5 

228.6 

222.0 

307.9 

324.1 

365.8 

385.0 

465 

466 

413,9 

224.0 

230.0 

229.2 

222.5 

308.6 

324.8 

366.6 

385.9 

466 

467 

414  8 

224.6 

230.6 

229,7 

223.1 

309.2 

325.5 

367.3 

386.7 

467 

468 

415,7 

225.1 

231.2 

230.3 

223.7 

309.9 

326.2 

368.1 

387,5 

468 

469 

416.6 

225.7 

231.7 

230.9 

224.2 

310.6 

326.9 

368.9 

388,3 

469 

470 

417.5 

226.2 

232.3 

231.4 

224.8 

311.3 

327.7 

369,7 

3S9.2 

470 

471 

418,4 

226.8 

232.8 

232.0 

225.3 

312.0 

328.4 

370,5 

390,0 

471 

472 

419,3 

227.4 

233.4 

232.5 

225.9 

312.6 

329.1 

371,3 

390,8 

472 

473 

420.2 

227,9 

234.0 

2.33.1 

226.4 

313.3 

329,8 

372,1 

391,7 

473 

474 

421,0 

228,5 

234.5 

233,7 

227.0 

314.0 

330.5 

372.9 

392,5 

474 

475 

421,9 

229,0 

235.1 

234,2 

227.6 

314.7 

331,3 

373.7 

393,3 

475 

476 

422  8 

229,6 

235.7 

234,8 

228.1 

315.4 

332,0 

374.4 

394,2 

476 

477 

423,7 

230.1 

236.2 

235,4 

228.7 

316.1 

332,7 

375.2 

395,0 

477 

478 

424,6 

230.7 

236.8 

235,9 

229.2 

316,7 

333.4 

376,0 

395.8 

478 

479 

425.5 

231.3 

237.4 

236,5 

229,8 

317.4 

334.1 

376,8 

396.6 

479 

480 

426.4 

031  8 

237.9 

237,1 

230,3 

318.1 

334.8 

377,6 

397.5 

480 

481 

427.3 

232;  4 

238.5 

237,6 

230,9 

318.8 

335.6 

378,4 

398.3 

481 

482 

428,1 

232.9 

239.1 

.238.2 

231,5 

319,5 

336  3 

379,2 

399.1 

482 

483 

429,0 

233.5 

239,6 

238,8 

232,0 

320.1 

337.0 

380.0 

400.0 

483 

484 

429,9 

234.1 

240,2 

239,3 

232,6 

320.8 

337.7 

380.7 

400.8 

484 

485 

430,8 

234.6 

240,8 

239,9 

233,2 

321.5 

338.4 

381.5 

401.6 

485 

486 

431.7 

235.2 

241,4 

240.5 

2.33,7 

322.2 

339,1 

382.3 

402.4 

486 

487 

432.6 

235,7 

241,9 

241,0 

2.34.3 

322.9 

339.9 

383,1 

403,3 

487 

488 

433,5 

236,3 

242,5 

241,6 

234.8 

323.6 

340,6 

383,9 

404,1 

488 

489 

434,4 

236.9 

243.1 

242,2 

235,4 

324.2 

341,3 

384,7 

404,9 

489 

490 

435.3 

237.4 

243.6 

242,7 

236.0 

324.9 

342,0 

385.5 

405,8 

490 

28 


II.  A.  H.  Low  Volumetric  Method,  Modified.^ — Tentative. 


Standard  thiosulphate  solution. — Prepare  a  solution  of  sodium  thiosulphate 
containing  19  grams  of  pure  crystals  in  1  liter.  Weigh  accurately  about  0.2 
gram  of  pure  copper  foil  and  place  in  a  flask  of  250  cc.  capacity.  Dissolve  by  warming 
with  5  cc.  of  a  mixture  of  equal  volumes  of  strong  nitric  acid  and  water.  Dilute 
to  50  cc,  boil  to  expel  the  red  fumes,  add  5  cc.  of  strong  bromin  water,  and  boil 


Vni]  FOODS   AND    FEEDING    STUFFS  97 

until  the  bromin  is  completely  driven  off.  Remove  from  the  heat  and  add  a  slight 
excess  of  strong  ammonium  hydroxid  (about  7  cc.  is  required).  Again  boil  until 
the  excess  of  ammonia  is  expelled,  as  shown  by  a  change  of  color  of  the  liquid, 
and  a  partial  precipitation.  Then  add  a  slight  excess  of  strong  acetic  acid  (3  or  4 
cc.  of  80%  acid)  and  boil  for  a  minute.  Cool  to  room  temperature  and  add  10  cc. 
of  30%  potassium  iodid  solution.  Titrate  at  once  with  the  thiosulphate  solution 
until  the  brown  tinge  has  become  weak,  then  add  sufficient  starch  indicator  [VII, 
3  (a)l  to  produce  a  marked  blue  coloration.  Continue  the  titration  cautiously 
until  the  color  due  to  free  iodin  has  entirely  vanished.  The  blue  color  changes  to- 
ward the  end  to  a  faint  lilac.  If  at  this  point  the  thiosulphate  be  added  drop  by  drop 
and  a  little  time  allowed  for  complete  reaction  after  each  addition,  there  is  no  diffi- 
culty in  determining  the  end  point  within  a  single  drop.  One  cc.  of  the  thiosulphate 
solution  will  be  found  to  correspond  to  about  0.005  gram  of  copper. 


29 


DETERMINATION. 


After  washing  the  precipitated  cuprous  oxid,  cover  the  Gooch  with  a  watch 
glass  and  dissolve  the  oxid  by  means  of  5  cc.  of  warm  nitric  acid  (1  to  1)  poured  under 
the  watch  glass  with  a  pipette.  Catch  the  filtrate  in  a  250  cc.  flask,  wash  the 
watch  glass  and  Gooch  free  of  copper,  using  about  50  cc.  of  water.  Boil  to  expel 
red  fumes,  add  5  cc.  of  bromin  water,  boil  off  the  bromin,  and  proceed  exactly  as 
in  28. 

30  ///.  Volumetric  Permanganate  Method. — Tentative. 

Filter  and  wash  the  cuprous  oxid  as  directed  under  25.  Transfer  the  asbestos 
film  to  the  beaker,  add  about  30  cc.  of  hot  water,  and  beat  the  precipitate  and  asbes- 
tos thoroughly.  Rinse  the  crucible  with  50  cc.  of  a  hot  saturated  solution  of  ferric 
sulphate  in  20%  sulphuric  acid,  receiving  the  rinsings  in  the  beaker  containit)g  the 
precipitate.  After  the  cuprous  oxid  is  dissolved,  wash  the  solution  into  a  large 
Erlenmeyer  flask  and  immediately  titrate  with  a  standard  solution  of  potassium 
permanganate,  1  cc.  of  which  should  he  equivalent  to  0.010  gram  of  copper.  Stand- 
ardize this  solution  by  making  6  or  more  determinations  with  the  same  sugar  solu- 
tion, titrating  one  half  of  the  precipitates  obtained,  and  determining  the  copper  in 
the  others  by  electrolysis.  The  average  weight  of  copper  obtained  by  electrolysis, 
divided  by  the  average  number  of  cc.  of  permanganate  solution  required  for  the 
titrations,  gives  the  weight  of  copper  equivalent  to  1  cc.  of  the  standard  perman- 
ganate solution.  A  solution  standardized  with  iron  or  oxalic  acid  will  give  too  low 
a  result. 

31  IV.  Electrolytic  Deposition  from  Sulphuric  Acid  Solution. — Tentative. 

Filter  the  cuprous  oxid  in  a  Gooch,  wash  the  beaker  and  the  precipitate  thoroughly 
with  hot  water  without  transferring  the  precipitate  to  the  filter.  Wash  the  asbestos 
film  and  the  adhering  cuprous  oxid  into  the  beaker  by  means  of  hot  dilute  nitric  acid. 
After  the  copper  is  all  in  solution,  refilter  through  a  thin  film  of  asbestos  in  a  Gooch 
and  wash  thoroughly  with  hot  water.  Add  10  cc.  of  sulphuric  acid  (1  to  4),  and 
evaporate  the  filtrate  on  the  steam  bath  until  the  copper  salt  has  largely  crystal- 
lized. Heat  carefully  on  a  hot  plate  or  over  asbestos  until  the  evolution  of  white 
fumes  shows  that  the  excess  of  nitric  acid  is  removed.  Add  8-10  drops  of  nitric  acid 
(sp.  gr.  1.42)  and  rinse  into  a  100-125  cc.  platinum  dish.     Deposit  the  copper  by 


98  METHODS    OF   ANALYSIS  [Chap. 

electrolysis.  Wash  thoroughly  with  water,  then  break  the  current,  wash  with  alco- 
hol and  ether  successively,  dry  at  about  50°C.,  and  weigh.  If  preferred,  the  elec- 
trolysis can  be  conducted  in  a  beaker,  the  copper  being  deposited  upon  a  weighed 
platinum  electrode. 

32  V.  Electrolytic  Deposition  from  Sulphuric  and  Nitric  Acid  S  dulion. — Tenfative. 

Filter  and  wash  as  directed  under  31 .  Transfer  the  asbestos  film  from  the  cru- 
cible to  the  beaker  by  means  of  a  glass  rod  and  rinse  the  crucible  with  about  30  cc. 
of  a  boiling  mixture  of  dilute  sulphuric  and  nitric  acids,  containing  65  cc.  of  sul- 
phuric acid  (sp.  gr.  1.84)  and  50  cc.  of  nitric  acid  (sp.  gr.  1.42)  per  liter.  Heat  and 
agitate  until  solution  is  complete;  filter  and  electrolyze  as  under  31 . 

33  VI.  Electrolytic  Deposition  from  Nitric  Acid  Sdution. — Tentative. 

Filter  and  wash  as  directed  under  31 .  Transfer  the  asbestos  film  and  adhering 
oxid  to  the  beaker.  Dissolve  the  oxid  still  remaining  in  the  crucible  by  means. of 
2  cc.  of  nitric  acid  (sp.  gr.  1.42),  adding  it  with  a  pipette  and  receiving  the  solution 
in  the  beaker  containing  the  asbestos  film.  Rinse  the  crucible  with  a  jet  of  water, 
allowing  the  rinsings  to  flow  into  the  beaker.  Heat  the  contents  of  the  beaker  until 
the  copper  is  all  in  solution,  filter,  dilute  the  filtrate  to  a  volume  of  100  cc.  or  more, 
and  electrolyze.  When  a  nitrate  solution  is  electrolyzed,  the  first  washing  of  the 
deposit  should  be  made  with  water  acidulated  with  sulphuric  acid,  in  order  to  remove 
all  the  nitric  acid  before  the  current  is  interrupted. 

34  VII.  Reduction  in  Hydrogen. — Tentative. 

Deposit  an  asbestos  film  on  a  perforated  platinum  disc  or  cone  contained  in  a 
hard  glass  filtering  tube,  wash  free  from  loose  fibers,  dry  and  weigh.  Through  this 
tube,  previously  moistened,  filter  the  cuprous  oxid  immediately,  using  suction. 
Transfer  the  cuprous  oxid  to  the  tube  through  a  removable  funnel,  and  wash  thor- 
oughly with  hot  water,  alcohol  and  ether  successively.  After  drying,  connect  the 
tube  with  a  supply  of  dry  hydrogen,  heat  gently  until  the  cuprous  oxid  is  com- 
pletely reduced  to  metallic  copper,  cool  in  the  current  of  hydrogen,  and  weigh. 
If  preferred,  a  Gooch  crucible  may  be  used  for  the  filtration. 

Herzfeld  Gravimetric  Method. — Tentative. 

Method  I. 

(For  materials  containing  1.5%  or  less  of  invert  sugar  and  98.5%  or  more  of  sucrose.) 

35  REAGENTS. 

The  reagents  and  solutions  used  are  described  under  24. 

36  DETERMINATION. 

Prepare  the  solution  of  the  material  to  be  examined  so  as  to  contain  20  grams  in 
100  cc,  free  from  suspended  impurities  by  filtration  and  from  soluble  impurities  by 
neutral  lead  acetate,  removing  the  excess  of  lead  by  means  of  sodium  carbonate. 
Place  50  cc.  of  the  reagent  and  50  cc.  of  the  sugar  solution  in  a  250  cc.  beaker.  Heat 
this  mixture  at  such  a  rate  that  approximately  4  minutes  are  required  to  bring  it 
to  the  boiling  point,  and  boil  for  exactly  2  minutes.  Add  100  cc.  of  cold,  recently 
boiled,  water.  Filter  immediately  through  asbestos,  and  determine  the  copper 
by  one  of  the  methods  under  26,  29-34,  respectively.  Obtain  the  corresponding 
oercentage  of  invert  sugar  from  37. 


VIII] 


FOODS  AND  FEEDING  STUFFS 


37 


Table  2.— Herzfeld'S  Table. 


For  the  determination  of  invert  sugar  in  materials  containing  1.5%,  or  less,  of  invert 
sugar  and  98.5%,  or  more,  of  sucrose. 


COPPER 

C    PPER 

COPPER 

BEinCED  BT 
10  ORAM8 

INVERT   SUGAR 

REDUCED  BT 
10  ORAM3 

IKVERT  SUGAR 

REDUCED  BT 
10  <iRAMS 

IirVERT  BCOAR 

OF  MATERIAL 

OF  MATERIAL 

or  MATERIAL 

mg. 

per  cent 

mg. 

per  cent 

mg. 

per  cent 

50 

0.05 

140 

0.51 

230 

1.02 

55 

0.07 

145 

0.53 

235 

1.05 

60 

0.09 

150 

0.56 

240 

1.07 

65 

0.11 

155 

0.59 

245 

1.10 

70 

0.14 

160 

0.62 

250 

1.13 

75 

0.16 

165 

0.65 

255 

1.16 

80 

0.19 

170 

0.68 

260 

1.18 

85 

0.21 

175 

0.71 

265 

1.21 

90 

0.24 

180 

0.74 

270 

1.24 

95 

0.27 

185 

0.76 

275 

1.27 

100 

0.30 

190 

0.79 

280 

1.30 

105 

0.32 

195 

0.82 

285 

1.33 

110 

0.35 

200 

0.85 

290 

1.36 

115 

0.38 

205 

0.88 

295 

1.38 

120 

0.40 

210 

0.90 

300 

1.41 

125 

0.43 

215 

0.93 

305 

1.44 

130 

0.45 

220 

0.96 

310 

1.47 

135 

0.48 

225 

0.99 

315 

1.50 

Method  II. 
(For  materials  containing  1.5%  or  more  of  invert  sugar  and  98.5%  or  less  of  sucrose.) 

38 


REAGENTS. 


Same  as  described  under  24. 


39  DETERMINATION. 

Prepare  a  solution  of  the  material  to  be  examined  in  such  a  manner  that  it  con- 
tains 20  grams  in  100  cc.  after  clarification  and  removal  of  the  excess  of  lead.  Pre- 
pare a  series  of  solutions  in  large  test  tubes  by  adding  1,  2,  3,  4,  and  5  cc.  of  this 
solution  to  each  tube  successively.  Add5cc.  of  the  reagent  to  each,  heat  to  boiling, 
boil  2  minutes,  and  filter.  Note  the  volume  of  sugar  solution  which  gives  the  fil- 
trate lightest  in  tint,  but  still  distinctly  blue.  Place  20  times  this  vo  ume  of  the 
sugar  solution  in  a  100  cc.  flask,  dilute  to  the  mark,  and  mix  well.  Use  50  cc.  of  the 
solution  for  the  determination,  which  is  conducted  as  described  under  36.  For  the 
calculation  of  the  result  use  the  following  formulas  and  table  of  factors  of  Meissl 
and  Hiller: 

Let  Cu  =  the  weight  of  copper  obtained; 
P  =  the  polarization  of  the  sample; 
W    =  the  weight  of  the  sample  in  the  50  cc.  of  the  solution  used  for  the 

determination; 
F    =  the  factor  obtained  from  the  table  for  the  conversion  of  copper  to 
invert  sugar; 

Cu 
Then  —  =Z,  approximate  weight  of  invert  sugar; 


Z  X 


100 


=  Y,  approximate  per  cent  of  invert  sugar; 


100 


METHODS    OF   ANALYSIS 


[Chap. 


100  P 

P+  Y 

100 -R 

CuF 

W 


R,  approximate  per  cent  of  sucrose  in  mixture  of  sugars; 
I,  approximate  per  cent  of  invert  sugar; 
per  cent  of  invert  sugar. 


The  factor  F  for  calculating  copper  to  invert  sugar  is  then  found  from  40. 

40  Table  3. 

Meissl  and  Hiller's^  factors  for  determinations  in  materials  in  which,  of  tfie  total 
sugars  -present,  1.5%,  or  more,  is  invert  sugar,  and  98.5%,  or  less,  is  sucrose. 


APPROXIMATE    ABSOLUTE    WEIGHT 

OP  INVERT   SUGAR  (Z) 

RATIO  OF  SUCROSE 

TO  INVERT 

SUGAR  =  r:i. 

200 

175 

150 

125 

100 

75 

50 

milligrams 

milligrams 

milligrams 

milligrams 

milligrams 

milligrams 

milligrams 

per  cent 

per  cent 

per  cent 

per  cent 

per  cent 

per  cent 

per  cent 

0:100 

56.4 

55.4 

54.5 

53.8 

53.2 

53.0 

53.0 

10:90 

56.3 

55.3 

54.4 

53.8 

53.2 

52.9 

52.9 

20:80 

56.2 

55.2 

54.3 

53.7 

53.2 

52.7 

52.7 

30:70 

56.1 

55.1 

54.2 

53.7 

53.2 

52.6 

52.6 

40:60 

55.9 

55.0 

54.1 

53.6 

53.1 

52.5 

52.4 

50:50 

55.7 

54.9 

54.0 

53.5 

53.1 

52.3 

52.2 

60:40 

55.6 

54.7 

53.8 

53.2 

52.8 

52.1 

51.9 

70:30 

55.5 

54.5 

53.5 

52.9 

52.5 

51.9 

51,6 

80:20 

55.4 

54.3 

53.3 

52.7 

52.2 

51.7 

51.3 

90:10 

54.6 

53.6 

53.1 

52.6 

52.1 

51.6 

51.2 

91:9 

54.1 

53.6 

52.6 

52.1 

51.6 

51.2 

50.7 

92:8 

53.6 

53.1 

52.1 

51.6 

51.2 

50.7 

50.3 

93:7 

53.6 

53.1 

52.1 

51.2 

50.7 

50.3 

49.8 

94:6 

53.1 

52.6 

51.6 

50.7 

50.3 

49.8 

48.9 

95:5 

52.6 

52.1 

51.2 

50.3 

49.4 

48.9 

48.5 

96:4 

52.1 

51.2 

50.7 

49.8 

48.9 

47.7 

46.9 

97:3 

50.7 

50.3 

49.8 

48.9 

47.7 

46.2 

45.1 

98:2 

49.9 

48.9 

48.5 

47.3 

45.8 

43.3 

40.0 

99:1 

47.7 

47.3 

46.5 

45.1 

43.3 

41.2 

38.1 

Example:  The  polarization  of  a  sugar  is  86.4,  and  50  cc.  of  solution  containing 
3.256  grams  of  sample  gave  0.290  gram  of  copper. 

Cu      0.290 


= 

2 

2 

=  0.145  = 

Z 

Z  X  100 

w 

100 
=  «-^^^><  3.256  = 

4.45 

100  -  R  = 

=  100- 

95.1=  I  = 

-  4.9 

R:I 

=  95.1:4.9 

By  consulting  the  table  it  will  be  seen  that  the  vertical  column  headed  l/iO  is 
nearest  to  Z,  145,  and  the  horizontal  column  headed  95:  5  is  nearest  to  the  ratio  of 
R  to  I,  95.1  :  4.9.  Where  these  columns  meet,  we  find  the  factor  51.2  which  enters 
into  the  final  calculation: 


CuF 
W 


0.290  X  51.2 
3.256 


=  4.56  per  cent  of  invert  sugar. 


In  case  there  is  no  sucrose  present,  the  following  table  may  be  used  instead  of  the 
factors  given  in  40. 


VIII] 
41 


foods  and  feeding  stuffs 

Table  4.— Meissl-s  Table. ^ 
For  the  determination  of  invert  sugar  alonf,: 
[According  to  Wein.] 

[Expressed  in  milligrams.) 


101 


COPPER 

INVERT 
SUGAR 

COPPER 

INVERT 
SUGAR 

COPPER 

INVERT 
SUGAR 

COPPER 

1N\  ERT 
SUGAR 

90 

46.9 

135 

70.8 

180 

95.2 

225 

120.4 

91 

47.4 

136 

71.3 

181 

95.7 

226 

120.9 

92 

47.9 

137 

71.9 

182 

96.2 

227 

121.5 

93 

48.4 

138 

72.4 

183 

96.8 

228 

122.1 

94 

48.9 

139 

72.9 

184 

97.3 

229 

122.6 

95 

49.5 

140 

73.5 

185 

97.8 

230 

123.2 

96 

50.0 

141 

74.0 

186 

98.4 

231 

123.8 

97 

50.5 

142 

74.5 

187 

99.0 

232 

124.3 

98 

51.1 

143 

75.1 

188 

99.5 

233 

124.9 

99 

51.6 

144 

75.6 

189 

100.1 

234 

125.5 

100 

52.1 

145 

76.1 

190 

100.6 

235 

126.0 

101 

52.7 

146 

76.7 

191 

101.2 

236 

126.6 

102 

53.2 

147 

77.2 

192 

101.7 

237 

127.2 

103 

53.7 

148 

77.8 

193 

102.3 

238 

127.8 

104 

54.3 

149 

78.3 

194 

102.9 

239 

128.3 

105 

54.8 

150 

78.9 

195 

103.4 

240 

128.9 

106 

55.3 

151 

79.4 

196 

104.0 

241 

129.5 

107 

55.9 

152 

80.0 

197 

104.6 

242 

130.0 

108 

56.4 

153 

80.5 

198 

105.1 

243 

130.6 

109 

56.9 

154 

81.0 

199 

105.7 

244 

131.2 

110 

57.5 

155 

81.6 

200 

106.3 

245 

131.8 

111 

58.0 

156 

82.1 

201 

106.8 

246 

132.3 

112 

58.5 

157 

82.7 

202 

107.4 

247 

132.9 

113 

59.1 

158 

83.2 

203 

107.9 

248 

133.5 

114 

59.6 

159 

83.8 

204 

108.5 

249 

134.1 

115 

60.1 

160 

84.3 

205 

109.1 

250 

134.6 

116 

60.7 

161 

84.8 

206 

109.6 

251 

135.2 

117 

61.2 

162 

85.4 

207 

110.2 

252 

135.8 

118 

61.7 

163 

85.9 

208 

110.8 

253 

136.3 

119 

62.3 

164 

86.5 

209 

111.3 

254 

136.9 

120 

62.8 

165 

87.0 

210 

111.9 

255 

137.5 

121 

63.3 

166 

87.6 

211 

112.5 

256 

138.1 

122 

63.9 

167 

88.1 

212 

113.0 

257 

138.6 

123 

64.4 

168 

88.6 

213 

113.6 

258 

139.2 

124 

64.9 

169 

89.2 

214 

114.2 

259 

139.8 

125 

65.5 

170 

89.7 

215 

114.7 

260 

140.4 

126 

66.0 

171 

90.3 

216 

115.3 

261 

140.9 

127 

66.5 

172 

90.8 

217 

115.8 

262 

141.5 

128 

67.1 

173 

91.4 

218 

116.4 

263 

142.1 

129 

67.6 

174 

91.9 

219 

117.0 

264 

142.7 

130 

68.1 

175 

92.4 

220 

117.5 

265 

143.2 

131 

68.7 

176 

93.0 

221 

118.1 

266 

143.8 

132 

69.2 

177 

93.5 

222 

118.7 

267 

144.4 

133 

69.7 

178 

94.1 

223 

119.2 

268 

144.9 

134 

70.3 

179 

94.6 

224 

119.8 

269 

145.5 

102 


METHODS    OF   ANALYSIS 


[Chap. 


41.. 


Table  4. — Meissl'S  Table.— Continued, 

[Expressed  in  milligrams.! 


INVERT 

INVERT 

INVERT 

INVERT 

COPPEB 

BOQAR 

COPPER 

snoAR 

COPPER 

SUGAR 

COPPER 

SCOAR 

270 

146.1 

310 

169.7 

350 

193.8 

390 

218.7 

271 

146.7 

311 

170.3 

351 

194.4 

391 

219.3 

272 

147.2 

312 

170.9 

352 

195.0 

392 

219.9 

273 

147.8 

313 

171.5 

353 

195.6 

393 

220.5 

274 

148.4 

314 

172.1 

354 

196.2 

394 

221.2 

275 

149.0 

315 

172.7 

355 

196.8 

395 

221.8 

276 

149.5 

316 

173.3 

356 

197.4 

396 

222.4 

277 

150.1 

317 

173.9 

357 

198.0 

397 

223.1 

278 

150.7 

318 

174.5 

358 

198.6 

398 

223.7 

279 

151.3 

319 

175.1 

359 

199.2 

399 

224.3 

280 

151.9 

320 

175.6 

360 

199.8 

400 

224.9 

281 

152.5 

321 

176.2 

361  ' 

200.4 

401 

225.7 

282 

153.1 

322 

176.8 

362 

201.1 

402 

226.4 

283 

153.7 

323 

177.4 

363 

201.7 

403 

227.1 

284 

154.3 

324 

178.0 

364 

202.3 

404 

227.8 

285 

154.9 

325 

178.6 

365 

203.0 

405 

228.6 

286 

155.5 

326 

179.2 

366 

203.6 

406 

229.3 

287 

156.1 

327 

179.8 

367 

204.2 

407 

230.0 

288 

156.7 

328 

180.4 

368 

204.8 

408 

230.7 

289 

157.2 

329 

181.0 

369 

205.5 

409 

231.4 

290 

157.8 

330 

181.6 

370 

206.1 

410 

232.1 

291 

158.4 

331 

182.2 

371 

206.7 

411 

232.8 

292 

159.0 

332 

182.8 

372 

207.3 

412 

233.5 

293 

159.6 

333 

183.5 

373 

208.0 

413 

234.3 

294 

160.2 

334 

184.1 

374 

208.6 

414 

235.0 

295 

160.8 

335 

184.7 

375 

209.2 

415 

235.7 

296 

161.4 

336 

185.4 

376 

209.9 

416 

236.4 

297 

162.0 

337 

186.0 

377 

210.5 

417 

237.1 

298 

162.6 

338 

l.«6.6 

378 

211.1 

418 

237.8 

299 

163.2 

339 

187.2 

379 

211.7 

419 

238.6 

300 

163.8 

340 

187.8 

380 

212.4 

420 

239.2 

301 

161.4 

341 

188.4 

381 

213.0 

421 

239.9 

302 

165.0 

342 

189.0 

382 

213.6 

422 

240.6 

303 

165.6 

343 

189.6 

383 

214.3 

423 

241.3 

304 

166.2 

344 

190.2 

384 

214.9 

424 

242.0 

305 

166.8 

345 

190.8 

385 

215.5 

425 

242.7 

306 

167.3 

316 

191.4 

386 

216.1 

426 

243.4 

307 

167.9 

347 

192.0 

387 

216.8 

427 

244.1 

308 

168.5 

348 

192.6 

388 

217.4 

428 

244.9 

309 

169.1 

349 

193.2 

389 

218.0 

429 
430 

245.6 
246.3 

42 


MALTOSE. 
General  Gravimetric   Method. — Tentative. 


Proceed   as   directed  under  25  and  obtain,   from   27,    the   weight   of   maltose 
equivalent  to  the  weight  of  copper  reduced. 


VIII] 


FOODS   AND    FEEDING    STUFFS 


103 


Wein  Method. — Tentative. 

43  REAGENTS. 

The  reagents  and  solutions  used  are  described  under  24. 

44  DETERMINATION. 

Place  50  cc,  of  the  reagent  in  a  beaker  and  heat  to  the  boiling  point.  When 
boiling  briskly,  add  25  cc.  of  the  maltose  solution  containing  not  more  than  0.250 
gram  of  maltose  and  boil  for  4  minutes.  Filter  immediately  through  asbestos  and 
determine,  by  one  of  the  methods  given  under  26,  29-34  respectively,  the  amount  of 
copper  reduced. 
Obtain,  from  45,  the  weight  of  maltose  equivalent  to  the  weight  of  copper  found. 


45 


Table  5. 

For  the  determination  of  maltose. 

[According  to  Wein.»] 

[Expressed  in  milligrams.) 


COPPER 

ccr- 

PR008 
OXID 

UAh- 

TOSB 

COPPER 

CU- 
PROUS 
OXID 

MAL- 
TOSE 

COPPER 

cv- 

PROU8 
OXID 

MAL- 
TOSE 

COPPER 

CU- 
PROUS 
OXID 

MAL- 
TOSE 

31 

34.9 

26.1 

71 

79.9 

61.0 

111 

125.0 

96.4 

151 

170.0 

132.3 

32 

36.0 

27.0 

72 

81.1 

61.8 

112 

126.1 

97.3 

152 

171.1 

133.2 

33 

37.2 

27.9 

73 

82.2 

62.7 

113 

127.2 

98.1 

153 

172.3 

134  I 

34 

38.3 

28.7 

74 

83.3 

63.6 

114 

128.3 

154 

173.4 

135.0 

35 

39.4 

29.6 

75 

84.4 

64.5 

115 

129.6 

99^9 

155 

174.5 

135.9 

38 

40.5 

30.5 

76 

85.6 

65.4 

116 

130.6 

100.8 

156 

175.6 

136.8 

37 

41.7 

31.3 

77 

86.7 

66.2 

117 

131  7 

101  7 

157 

176.8 

137.7 

38 

42.8 

32.2 

78 

87.8 

67.1 

118 

132.8 

102.6 

158 

177.9 

138.6 

39 

43.9 

33.1 

79 

88.9 

68.0 

119 

134.0 

103.5 

159 

179  0 

1.39.5 

40 

45.0 

33.9 

80 

90.1 

68.9 

120 

135.1 

104.4 

160 

180.1 

140.4 

41 

46.2 

34.8 

81 

91.2 

69  7 

121 

136.2 

105.3 

161 

181.3 

141.3 

42 

47.3 

35.7 

82 

92.3 

70.6 

122 

137  4 

106.2 

162 

182  4 

142.2 

43 

48.4 

36  5 

83 

93.4 

71.5 

123 

138.5 

107.1 

163 

183.5 

143.1 

44 

49.5 

37.4 

84 

94.6 

72.4 

124 

139.6 

108.0 

164 

184.6 

144.0 

45 

60.7 

38.3 

85 

95.7 

73.2 

125 

140.7 

108.9 

165 

185.8 

144.9 

49 

51.8 

39.1 

86 

96.8 

74.1 

126 

141.9 

109  8 

166 

186.9 

145.8 

47 

52.9 

40.0 

87 

97.9 

75.0 

127 

143.0 

110.7 

167 

188.0 

146.7 

48 

54.0 

40.9 

88 

99.1 

75.9 

128 

144.1 

111.6 

168 

189.1 

147  6 

49 

55.2 

41.8 

89 

100.2 

76.8 

129 

145.2 

112.5 

169 

190.3 

148.5 

60 

66.3 

42.6 

90 

101  3 

77.7 

130 

146.4 

113.4 

170 

191.4 

149.4 

51 

57.4 

43.5 

91 

102  4 

78.6 

131 

147.5 

114.3 

171 

192.5 

150.3 

52 

68.5 

44.4 

92 

103.6 

79.5 

132 

148  6 

115  2 

172 

193  6 

151.3 

53 

59.7 

45.2 

93 

104.7 

80.3 

133 

149.7 

116.1 

173 

194.8 

152.0 

54 

60.8 

46.1 

94 

105.8 

81.2 

134 

150  9 

117.0 

174 

195.9 

152.9 

55 

61.9 

47.0 

95 

107.0 

82.1 

135 

152.0 

117.9 

175 

197.0 

153.8 

68 

63.0 

47.8 

96 

108.1 

83.0 

136 

153  1 

118.8 

176 

198.1 

154.7 

57 

64.2 

48.7 

97 

109.2 

83.9 

137 

154.2 

119.7 

177 

199.3 

155.6 

68 

65.3 

49.6 

98 

110.3 

84.8 

l.^S 

155.4 

120.6 

178 

200.4 

156.5 

69 

66  4 

50.4 

99 

111.5 

85.7 

139 

156.5 

121.5 

179 

201.5 

157.4 

60 

67.6 

51.3 

100 

112.6 

86.6 

140 

157.6 

122.4 

180 

202.6 

158.3 

61 

68.7 

52.2 

101 

113.7 

87.5 

141 

158.7 

123.3 

181 

203  8 

159.2 

62 

69.8 

53.1 

102 

114.8 

88.4 

142 

159.9 

124.2 

182 

204.9 

m.\ 

63 

70.9 

53.9 

103 

116.0 

89.2 

143 

lei.o 

125.1 

183 

20B  0 

lfiO.9 

64 

72.1 

54  8 

104 

117.1 

90.1 

144 

162  1 

126.0 

184 

207.1 

161.8 

65 

73.2 

65.7 

105 

118.2 

91.0 

145 

163.2 

126.9 

185 

208.3 

162.7 

66 

74.3 

56.6 

106 

119  3 

91.9 

146 

164.4 

127.8 

186 

209.4 

163  6 

67 

75.4 

67.4 

107 

120  5 

92.8 

147 

165.5 

128.7 

187 

210  5 

164  5 

68 

76.6 

58.3 

108 

121  6 

93.7 

148 

166.6 

129  6 

188 

211  7 

165  4 

69 

77.7 

59.2 

109 

122.7 

94  6 

149 

167.7 

130  5 

189 

212  8 

166  3 

70 

78.8 

60.1 

110 

123.8 

95.5 

150 

168.9 

131.4 

190 

213.9 

167.2 

104 
45 


46 


METHODS    OF   ANALYSIS 

Table  5. — Continued. 
For  the  determination  of  maltose. 

[Expressed  in  milligrams.) 


[Chap. 


CU- 

CU- 

CU- 

CU- 

COPPER 

PROUS 
OXID 

MAL- 
TOSE 

COPPER 

PROUS 
OXID 

MAL- 
TOSE 

COPPER 

PROUS 
OXID 

MAL- 
TOSE 

COPPER 

PROUS 
OXID 

MAL- 
TOSE 

191 

215.0 

168.1 

221 

248.7 

194.8 

251 

282.6 

221.7 

281 

316.4 

248.7 

192 

216.2 

169.0 

222 

249,9 

195.7 

252 

283  7 

222.6 

282 

317.5 

240.6 

193 

217.3 

169  8 

223 

251.0 

196.6 

253 

284.8 

223.5 

283 

318.6 

250.4 

194 

218.4 

170.7 

224 

2,52.4 

197.5 

254 

286.0 

224.4 

284 

319.7 

251.3 

195 

219.5 

171  6 

225 

253.3 

198.4 

255 

287.1 

225.3 

285 

320.9 

252.2 

196 

220.7 

172.5 

226 

254.4 

199.3 

256 

288.2 

226.2 

286 

322.0 

253.1 

197 

221.8 

173.4 

227 

255.6 

200.2 

257 

289.3 

227  1 

287 

323.1 

2.54.0 

198 

222.9 

174.3 

228 

256.7 

201.1 

258 

290.5 

228  0 

288 

324.2 

254.9 

199 

224.0 

175.2 

229 

257.8 

202  0 

259 

291  6 

228.9 

289 

325.4 

255.8 

200 

225.2 

176.1 

230 

258.9 

202.9 

260 

292.7 

229.8 

290 

326.5 

256.6 

201 

226.3 

177.0 

231 

260.1 

203.8 

261 

293.8 

230.7 

291 

327.4 

257.5 

202 

227.4 

177.9 

232 

261  2 

204.7 

262 

295.0 

231.6 

292 

328,7 

2.58.4 

203 

228.5 

178.7 

233 

262.3 

205.6 

263 

296.1 

232.5 

293 

329.9 

259.3 

204 

229.7 

179.6 

234 

263.4 

206.5 

264 

297.2 

2.33.4 

294 

331.0 

260.2 

205 

230.8 

180.5 

235 

264.6 

207.4 

265 

298.3 

234.3 

295 

332.1 

261.1 

206 

231.9 

181.4 

236 

265.7 

208.3 

266 

299  5 

235.2 

296 

333.2 

262.0 

207 

233.0 

182.3 

237 

266  8 

209  1 

267 

300.6 

236.1 

297 

334.4 

262.8 

208 

234.2 

183.2 

238 

268.0 

210  0 

268 

301.7 

2.37  0 

298 

335.5 

263.7 

209 

235.3 

184.1 

239 

269.1 

210.9 

269 

302  8 

237.9 

299 

336.6 

264.6 

210 

236.4 

185.0 

240 

270.2 

211.8 

270 

304.0 

238.8 

300 

337.8 

265.5 

211 

237.6 

185.9 

241 

271.3 

212.7 

271 

305,1 

239,7 

212 

238.7 

186.8 

242 

272.5 

213  6 

272 

306.2 

240.6 

213 

239.8 

187.7 

243 

273  6 

214.5 

273 

307.3 

241.5 

214 

240.9 

188.6 

244 

274.7 

215.4 

274 

308.5 

242.4 

215 

242.1 

189.5 

245 

275.8 

216.3 

275 

309.6 

243.3 

216 

243.2 

190.4 

246 

277.0 

217.2 

276 

310.7 

244  2 

217 

244.3 

191.2 

247 

278.1 

218  1 

277 

311.9 

245.1 

218 

245,4 

192.1 

248 

279.2 

219.0 

278 

313  0 

246.0 

219 

246.6 

193.0 

249 

280.3 

219.9 

279 

314.1 

246.9 

220 

247.7 

193.9 

250 

281.5 

220.8 

280 

315.2 

247.8 

LACTOSE. 

General  Gravimetric   Method. — Tentative. 


Proceed  as  directed   under  25   and  obtain,    from    27,    the   weight   of   lactose 
equivalent  to  the  weight  of  copper  reduced. 

Soxhlet-Wein    Method. — Official. 

47  REAGENTS. 

The  reagents  and  solutions  used  are  described  under  24. 


48 


DETERMINATION. 


Place  50  cc.  of  the  reagent  in  a  beaker  and  heat  to  the  boiling  point.  When 
boiling  briskly,  add  100  cc.  of  the  lactose  solution  containing  not  more  than  0.300 
gram  of  lactose  and  boil  for  6  minutes.  Filter  immediately  through  asbestos  and 
determine  by  one  of  the  methods  given  under  26,  29-34  inclusive,  the  amount  of 
copper  reduced.  Obtain,  from  49,  the  weight  of  lactose  equivalent  to  the  weight  of 
copper  found. 


vni] 

49 


FOODS  AND  FEEDING  STUFFS 

Table  6. 

For  the  determination  of  lactose  (Soxhlei-Wein^). 

[Expressed  in  milligrams. ) 


105 


COPPER 

LACTOSE 

COPPER 

LACTOSE 

COPPER 

LACTOSE 

COPPER 

LACTOSE 

COPPER 

LACTOSE 

100 

71.6 

160 

116.4 

220 

161.9 

280 

208.3 

340 

255.7 

101 

72.4 

161 

117.1 

221 

162.7 

281 

209.1 

341 

256.5 

102 

73.1 

162 

117.9 

222 

163.4 

282 

209.9 

342 

257.4 

103 

73.8 

163 

118.6 

223 

164.2 

283 

210.7 

343 

2.58.2 

104 

74.6 

164 

119.4 

224 

164.9 

284 

211.5 

344 

259.0 

105 

75.3 

165 

120.2 

225 

165.7 

285 

212.3 

345 

259.8 

106 

76.1 

186 

120.9 

226 

166.4 

286 

213.1 

346 

260.6 

107 

76.8 

167 

121.7 

227 

167.2 

287 

213.9 

347 

261.4 

108 

77.6 

168 

122.4 

228 

167.9 

288 

214.7 

348 

262.3 

109 

78.3 

169 

123.2 

229 

168.6 

289 

215.5 

349 

263.1 

110 

79.0 

170 

123.9 

230 

169.4 

290 

216.3 

350 

263.9 

111 

79.8 

171 

124.7 

231 

170.1 

291 

217.1 

351 

264.7 

112 

80.5 

172 

125.5 

232 

170.9 

292 

217.9 

352 

265.5 

113 

81  3 

173 

126.2 

233 

171.6 

293 

218.7 

353 

266.3 

114 

82.0 

174 

127.0 

234 

172.4 

294 

219.5 

354 

267.2 

115 

82.7 

175 

127.8 

235 

173.1 

295 

220.3 

355 

268.0 

116 

83  5 

176 

128.5 

236 

173.9 

296 

221.1 

356 

268.8 

117 

84.2 

177 

129.3 

237 

174.6 

297 

221.9 

357 

269.6 

118 

85.0 

178 

130.1 

238 

175  4 

298 

222.7 

358 

270.4 

119 

85.7 

179 

130.8 

239 

176.2 

299 

223.5 

359 

271.2 

120 

86.4 

180 

131.6 

240 

176.9 

300 

224.4 

360 

272.1 

121 

87.2 

181 

132.4 

241 

177.7 

301 

225.2 

361 

272.9 

122 

87.9 

182 

133.1 

242 

178.5 

302 

225  9 

362 

273.7 

123 

88.7 

183 

133.9 

243 

179.3 

303 

226.7 

363 

274.5 

124 

89.4 

184 

134.7 

244 

180.1 

304 

227.5 

304 

275.3 

125 

90.1 

185 

135.4 

245 

180.8 

305 

228.3 

365 

276.2 

120 

90.9 

186 

136.2 

246 

181.6 

306 

229.1 

366 

277.1 

127 

91.6 

187 

137.0 

247 

182.4 

307 

229  8 

367 

277.9 

128 

92.4 

188 

137.7 

248 

183.2 

308 

230.6 

278.8 

129 

93.1 

189 

138.5 

249 

184.0 

309 

231.4 

369 

279.6 

130 

93.8 

190 

1.39.3 

250 

184.8 

310 

232.2 

370 

280.5 

131 

94.6 

191 

140.0 

251 

185.5 

311 

232  9 

371 

281.4 

132 

95.3 

192 

140.8 

252 

186.3 

312 

233.7 

372 

282.2 

133 

96.1 

193 

141.6 

253 

187.1 

313 

234.5 

373 

283.1 

134 

96.9 

194 

142.3 

254 

187.9 

314 

235.3 

374 

283.9 

135 

97.6 

195 

143.1 

255 

188.7 

315 

236.1 

375 

284.8 

136 

98.3 

196 

143.9 

256 

189.4 

316 

2.36.8 

376 

285.7 

137 

99  1 

197 

144.6 

257 

190.2 

317 

2,37.6 

377 

286.5 

138 

99.8 

198 

145.4 

258 

191.0 

318 

2.38.4 

378 

287.4 

139 

100.5 

199 

146.2 

259 

191.8 

319 

239.2 

379 

288.2 

140 

101.3 

200 

146.9 

260 

192.5 

320 

240  0 

380 

289.1 

141 

102.0 

201 

147.7 

261 

193.3 

321 

240.7 

381 

289.9 

142 

102.8 

202 

148.5 

262 

194.1 

322 

241.5 

382 

290.8 

143 

103.5 

203 

149.2 

263 

194.9 

323 

242.3 

383 

291.7 

144 

104.3 

204 

150.0 

264 

195.7 

324 

243.1 

384 

292.5 

145 

105.1 

205 

150.7 

265 

196.4 

325 

243.9 

385 

293.4 

146 

105.8 

206 

151.5 

266 

197  2 

326 

244.6 

386 

294.2 

147 

106.0 

207 

152.2 

267 

198.0 

327 

245.4 

387 

295.1 

148 

107.3 

208 

153.0 

268 

198.8 

328 

246.2 

388 

296.0 

149 

lOS.l 

209 

153.7 

269 

199.5 

329 

247.0 

389 

296.8 

150 

10S.8 

210 

154.5 

270 

200.3 

330 

247.7 

390 

297.7 

151 

109.6 

211 

155.2 

271 

201.1 

331 

248.5 

391 

298.5 

152 

110.3 

212 

1.56.0 

272 

201.9 

332 

249.2 

392 

299.4 

153 

111  1 

213 

1.56.7 

273 

202.7 

333 

250.0 

393 

300.3 

154 

111.9 

214 

157.5 

274 

203.5 

334 

250.8 

394 

301.1 

155 

112.6 

215 

15S.2 

275 

204.3 

335 

251.6 

395 

302.0 

156 

113  4 

216 

159  0 

276 

205.1 

336 

252  5 

396 

302.8 

157 

114.1 

217 

159.7 

277 

205.9 

337 

253.3 

397 

303.7 

158 

114.9 

218 

160.4 

278 

206.7 

338 

254.1 

398 

304.6 

159 

115.6 

219 

161.2 

279 

207.5     I 

339 

254.9 

399 
400 

305.4 
306.3 

106  METHODS    OF   ANALYSIS  [Chap. 

DEXTROSE. 

50  Approximate  Volumetric  Method  for  Rapid  Work. — Tentative. 
Proceed  as  directed  under  21 .     Standardize  the  reagent  against  pure  dextrose. 

51  Soxhlet  Method.— Tentative. 

Proceed  as  directed  under  23.     Under  these  conditions  100  cc.  of  the  reagent 

require  0.475  gram  of  anhydrous  dextrose  for  complete  reduction  and  the  formula 

100  X  0.475  .    r  ^     . 

becomes  ; =  per  cent  of  dextrose. 

VW 

52  General  Gravimetric  Method. — Tentative. 

Proceed  as  directed  under  25  and  obtain,  from  27,  the  weight  of  dextrose  equiv- 
alent to  the  weight  of  copper  reduced. 

Allihn  Gravimetric  Method. — Tentative. 

53  REAGENT. 

Allihn' s  Modification  of  Fehling's  Solution. — Prepare  by  mixing,  immediately 
before  use,  equal  volumes  of  (a)  and  (b). 

(a)  Copper  sulphate  solution. — Dissolve  34.639  grams  of  copper  sulphate 
(CuS045H,0)  in  water  and  dilute  to  500  cc. 

(b)  Alkaline  tartrate  soZuh'on.— Dissolve  173  grams  of  Rochelle  salts  and  125 
grams  of  potassium  hydroxid  in  water  and  dilute  to  500  cc. 

54  DETERMINATION. 

Place  30  cc.  of  the  copper  sulphate  solution,  30  cc.  of  the  alkaline  tartrate  solu- 
tion, and  60  cc.  of  water  in  a  beaker  and  heat  to  boiling.  Add  25  cc.  of  the  solution 
of  the  material  to  be  examined,  prepared  so  as  not  to  contain  more  than  0.25  gram 
of  dextrose,  and  boil  for  exactly  2  minutes,  keeping  the  beaker  covered.  Filter 
immediately  through  asbestos,  and  obtain  the  weight  of  copper  by  one  of  the  methods 
given  under  26,  29-34  inclusive.  The  corresponding  weight  of  dextrose  is  found 
in  55. 


vm] 

55 


FOODS   AND    FEEDING    STUFFS 

Table  7.— Allihn-s  Table. i" 
For  the  determination  of  dextrose. 

(Expressed  in  milligrams.) 


107 


COPPER 

cu- 
PRons 

OXID 

DEX- 
TROSE 

COPPER 

cu- 
1  Roua 

O  -ID 

DEX- 
TROSE 

COPPER 

CU- 
PROUS 
OXID 

DEX- 
TROSE 

COPPER 

CU- 
PROUS 
OXID 

DEX- 
TROSE 

11 

12.4 

6.6 

71 

79.9 

36.3 

131 

147.5 

66.7 

191 

215.0 

97.8 

12 

13.5 

7.1 

72 

81.1 

36.8 

132 

148.6 

67.2 

192 

216.2 

98.4 

13 

14.6 

7.6 

73 

82.2 

37.3 

133 

149.7 

67.7 

193 

217.3 

98.9 

14 

15.8 

8,1 

74 

83.3 

37.8 

134 

150.9 

68  2 

194 

218.4 

99.4 

15 

16.9 

8.8 

75 

84.4 

38.3 

135 

152.0 

68.8 

195 

219.5 

100.0 

16 

18.0 

9.0 

76 

85.6 

38.8 

136 

153.1 

69.3 

196 

220.7 

100.5 

17 

19.1 

9.5 

77 

86.7 

39.3 

137 

154,2 

69.8 

197 

221.8 

101.0 

18 

20.3 

10.0 

78 

87.8 

39.8 

138 

155.4 

70.3 

198 

222.9 

101.5 

19 

21.4 

10.5 

79 

88.9 

40.3 

139 

156.5 

70.8 

199 

224.0 

102.0 

20 

22.5 

11.0 

80 

90.1 

40.8 

140 

157.6 

71.3 

200 

225.2 

102.9 

21 

23.6 

11.5 

81 

91.2 

41.3 

141 

158.7 

71.8 

201 

226.3 

103.1 

22 

24.8 

12.0 

82 

92.3 

41.8 

142 

159.9 

72  3 

202 

227.4 

103.7 

23 

25.9 

12.5 

83 

93.4 

42.3 

143 

161.0 

72.9 

203 

228.5 

104.2 

24 

27.0 

13.0 

84 

94.6 

42.8 

144 

162.1 

73.4 

204 

229.7 

104.7 

25 

28.1 

13.5 

85 

95.7 

43.4 

145 

163.2 

73.9 

205 

230.8 

105.3 

26 

29.3 

14.0 

86 

96.8 

43.9 

146 

164.4 

74.4 

206 

231.9 

105.8 

27 

30.4 

14.5 

87 

97.9 

44.4 

147 

165.5 

74.9 

207 

233.0 

108.3 

28 

31.5 

15.0 

88 

99.1 

44.9 

148 

166.6 

75.5 

208 

234.2 

106.8 

29 

32.7 

15.5 

89 

100.2 

45.4 

149 

167.7 

76.0 

209 

235.3 

107.4 

30 

33.8 

16.0 

90 

101  3 

45.9 

150 

168.9 

76.5 

210 

236.4 

107.9 

31 

34.9 

16.5 

91 

102.4 

46.4 

151 

170.0 

77.0 

211 

237.6 

108.4 

32 

36.0 

17.0 

92 

103.6 

46.9 

152 

171.1 

77.5 

212 

238.7 

109.0 

33 

37.2 

17.5 

93 

104.7 

47.4 

153 

172.3 

78.1 

213 

239  8 

109.5 

34 

38.3 

18.0 

94 

105.8 

47.9 

154 

173.4 

78.6 

214 

240.9 

110  0 

35 

39.4 

18.5 

95 

107.0 

48.4 

155 

174.5 

79.1 

215 

242.1 

110. « 

36 

40  5 

18.9 

96 

108.1 

48.9 

156 

175.6 

79.6 

216 

243.2 

111.1 

37 

41.7 

19.4 

97 

109.2 

49.4 

157 

176.8 

80.1 

217 

244.3 

111.8 

38 

42.8 

19.9 

98 

110.3 

49.9 

158 

177.9 

80.7 

218 

245.4 

112.1 

39 

43.9 

20.4 

99 

111.5 

50.4 

159 

179.0 

81.2 

219 

246.6 

112.7 

40 

45.0 

20.9 

100 

112.6 

50.9 

160 

180.1 

81.7 

220 

247.7 

113.2 

41 

46.2 

21.4 

101 

113.7 

51.4 

161 

181.3 

82.2 

221 

248.7 

113.7 

42 

47.3 

21.9 

102 

114.8 

51.9 

162 

182.4 

82.7 

222 

249.9 

114.3 

43 

48  4 

22.4 

103 

116.0 

52.4 

163 

183.5 

83,3 

223 

251.0 

114.8 

44 

49.5 

22.9 

104 

117.1 

52.9 

164 

184.6 

83.8 

224 

252.4 

115.3 

45 

50.7 

23.4 

105 

118.2 

53.5 

165 

185.8 

84.3 

225 

253.3 

115.9 

46 

51.8 

23.9 

106 

119.3 

54.0 

166 

186.9 

84.8 

226 

254.4 

116.4 

47 

52.9 

24.4 

107 

120.5 

54.5 

167 

188.0 

85.3 

227 

255.6 

116.9 

48 

54  0 

24.9 

108 

121.6 

55.0 

168 

189.1 

85.9 

228 

256.7 

117.4 

49 

55.2 

25.4 

109 

122.7 

55.5 

169 

190.3 

86.4 

229 

257.8 

118.0 

60 

56.3 

25.9 

110 

123.8 

56.0 

170 

191.4 

86.9 

230 

258.9 

118.5 

51 

57.4 

26.4 

111 

125.0 

56.5 

171 

192.5 

87.4 

231 

260.1 

119.0 

52 

58.5 

26.9 

112 

126.1 

57.0 

172 

193.6 

87.9 

232 

261.2 

119.6 

53 

59.7 

27.4 

113 

127.2 

57.5 

173 

194.8 

88.5 

233 

262.3 

120.1 

54 

60.8 

27.9 

114 

128.3 

58.0 

174 

195.9 

89.0 

234 

263.4 

120.7 

55 

61.9 

28.4 

115 

129.6 

58.6 

175 

197.0 

89.5 

235 

264.6 

121.2 

56 

63.0 

28.8 

116 

130  6 

59.1 

176 

198.1 

90.0 

236 

265.7 

121.7 

57 

64.2 

29.3 

117 

131.7 

59.6 

177 

199.3 

90.5 

237 

266.8 

122.3 

58 

65.3 

29.8 

118 

132.8 

60.1 

178 

200.4 

91.1 

238 

268.0 

122.8 

59 

66.4 

30.3 

119 

134.0 

60.6 

179 

201.5 

91.6 

239 

269.1 

123.4 

60 

67.6 

10.8 

120 

135.1 

61.1 

180 

202.6 

92.1 

240 

270.2 

123.0 

fil 

68.7 

31.3 

121 

136.2 

61.6 

181 

203.8 

92.6 

241 

271.3 

124.4 

62 

69.8 

31.8 

122 

137.4 

62.1 

182 

204.9 

93.1 

242 

272.5 

125.0 

63 

70.9 

32.3 

123 

1.38.5 

62.6 

183 

206.0 

93.7 

243 

273.6 

125.6 

64 

72.1 

32.8 

124 

139.6 

63  1 

184 

207.1 

94.2 

244 

274.7 

129.0 

65 

73.2 

33.3 

125 

140.7 

63.7 

185 

208.3 

94.7 

245 

275.8 

129.  S 

66 

74.3 

33.8 

126 

141  9 

64.2 

186 

209.4 

95.2 

246 

277.0 

127.1 

67 

75.4 

34.3 

127 

143.0 

64.7 

187 

210.5 

95.7 

247 

278.1 

127.9 

6S 

76.6 

34.8 

128 

144  1 

65.2 

188 

211.7 

96.3 

248 

279.2 

128.1 

69 

77.7 

35.3 

129 

145.2 

65.7 

189 

212.8 

96.8 

249 

280.3 

128  7 

70 

78.8 

35.8 

130 

146.4 

66.2 

190 

213.9 

97.3 

250 

281.5 

129.2 

108 
55 


METHODS    OF   ANALYSIS 

Table  7.— Allihns  Table. — Continued. 

[Expressed  in  milligrams.] 


[Chap. 


co- 

cn- 

CU- 

CU- 

COPPER 

pnons 

OXID 

DEX- 
TROSE 

COPPER 

PRODS 
OXID 

DEX- 
TROSE 

COPPER 

PROUS 
OXID 

DEX- 
TROSE 

COPPER 

PROUS 
OXID 

DEX- 
TROSE 

251 

282.6 

129.7 

306 

344.5 

159.8 

361 

406.4 

190.6 

416 

468.4 

222,2 

252 

283.7 

130.3 

307 

345.6 

160.4 

362 

407  6 

191.1 

417 

469,5 

222,8 

253 

284.8 

130.8 

308 

346.8 

160.9 

363 

408.7 

191.7 

418 

470,6 

223  3 

254 

286.0 

131.4 

309 

347.9 

161.5 

364 

409  8 

192.3 

419 

471  8 

223  9 

255 

287.1 

131.9 

310 

349.0 

162.0 

410.9 

192  9 

420 

472,9 

224.5 

256 

288.2 

132.4 

311 

3.50  1 

162.6 

366 

412  1 

193.4 

421 

474,0 

225,1 

257 

289.3 

133  0 

312 

351.3 

163  1 

367 

413.2 

194.0 

422 

475  6 

225  7 

258 

290  5 

133.5 

313 

352.4 

163.7 

368 

414  3 

194.6 

423 

476  2 

226  3 

259 

291.6 

134.1 

314 

353.5 

164.2 

369 

415.4 

195.1 

424 

477  4 

226,9 

260 

292.7 

134.6 

315 

354.6 

164.8 

370 

416  6 

195.7 

425 

478.5 

227.5 

261 

293.8 

135.1 

316 

355.8 

165.3 

371 

417  7 

196  3 

426 

479  6 

228.0 

262 

295.0 

135.7 

317 

356.9 

165  9 

372 

418. S 

196.8 

427 

480,7 

228.6 

263 

296.1 

1.36.2 

318 

3.58.0 

166.4 

373 

420.0 

197.4 

428 

481  9 

229,2 

264 

297.2 

136.8 

319 

359  1 

167.0 

374 

421.1 

198.0 

429 

483,0 

229  8 

265 

298.3 

137.3 

320 

360.3 

167.5 

375 

422.2 

198.6 

430 

484.1 

230.4 

266 

299.5 

137.8 

321 

361  4 

168.1 

376 

423.3 

199.1 

431 

485  3 

231,0 

267 

300.6 

138.4 

322 

362.5 

168.6 

377 

424  5 

199,7 

432 

486  4 

231,6 

268 

301.7 

1.38  9 

323 

363.7 

169.2 

378 

425  6 

200  3 

433 

487,5 

232,2 

269 

302.8 

139.5 

324 

364.8 

169  7 

379 

426.7 

200.8 

434 

488,6 

232.8 

270 

304.0 

140.0 

325 

365.9 

170.3 

380 

427.8 

201.4 

435 

489.7 

233.4 

271 

305,1 

140.6 

326 

367.0 

170  3 

381 

429  0 

202.0 

436 

490,9 

233.9 

272 

306.2 

141.1 

327 

368.2 

171.4 

382 

4.30  1 

202  5 

437 

492,0 

2.34.5 

273 

307.3 

141.7 

328 

369.3 

172.0 

383 

431.2 

203.1 

438 

493,1 

2.35.1 

274 

308.5 

142  2 

329 

370.4 

172  5 

384 

432.3 

203,7 

439 

494,3 

235.7 

275 

309.6 

142.8 

330 

371.5 

173.1 

385 

433.5 

204.3 

440 

495,4 

236.3 

■276 

310.7 

143.3 

331 

372.7 

173.7 

386 

434.6 

204.8 

441 

496.5 

236.9 

277 

143.9 

332 

373.8 

174.2 

387 

435.7 

205,4 

442 

497.6 

237  5 

278 

313:0 

144.4 

333 

374.9 

174.8 

388 

4.36.8 

206,0 

443 

498  8 

238  1 

279 

314.1 

145.0 

334 

376.0 

175.3 

438.0 

205  5 

444 

499,9 

238,7 

.280 

315.2 

145.5 

335 

377.2 

175.9 

390 

439.1 

207.1 

445 

501.0 

239.3 

281 

316.4 

146.1 

336 

378.3 

176.5 

391 

440.2 

207,7 

446 

502,1 

239.8 

282 

317.5 

146.6 

337 

379.4 

177.0 

392 

441.3 

208,3 

447 

503,2 

240.4 

283 

318.6 

147.2 

338 

380.5 

177.6 

393 

442.4 

208,8 

448 

504,4 

241  0 

284 

319  7 

147.7 

339 

381.7 

178.1 

394 

443.6 

209,4 

449 

505,5 

241.6 

285 

320.9 

148.3 

340 

382.8 

178.7 

395 

444.7 

210  0 

450 

506  6 

242.2 

286 

322.0 

148.8 

341 

383.9 

179.3 

396 

445.9 

210,6 

451 

507.8 

242.8 

287 

323  1 

149  4 

342 

385.0 

179.8 

397 

447.0 

211.2 

452 

508,9 

243.4 

288 

324.2 

149.9 

343 

386.2 

180  4 

398 

448.1 

211  7 

453 

510,0 

244.0 

289 

325.4 

150.5 

344 

387.3 

180.9 

449  2 

212,3 

454 

511,1 

244,6 

290 

326.5 

151.0 

345 

388.4 

181.5 

400 

450  3 

212,9 

455 

512.3 

245.2 

291 

327.4 

151.6 

346 

389.6 

182.1 

401 

451.5 

213,5 

456 

513.4 

245.7 

292 

328  7 

152.1 

347 

390.7 

182.6 

402 

452.6 

214.1 

457 

511,5 

246.3 

293 

329.9 

152.7 

348 

391.8 

183.2 

403 

453.7 

214,6 

458 

515  6 

246.9 

294 

331.0 

l.')3.2 

349 

392  9 

183.7 

404 

454.8 

215.2 

459 

516  8 

247.5 

295 

332.1 

153.8 

350 

394.0 

184.3 

405 

456.0 

215.8 

460 

517,9 

248.1 

296 

333.3 

154.3 

351 

395.2 

184.9 

406 

457.1 

216,4 

461 

519,0 

248,7 

297 

334.4 

154  9 

352 

396.3 

185.4 

407 

458.2 

217,0 

462 

520  1 

249,3 

298 

3.35.5 

1.55.4 

353 

397.4 

186.0 

408 

459.4 

217.5 

463 

521.3 

249.9 

299 

3.36.6 

1.56.0 

354 

398  6 

186  6 

409 

460.5 

218  1 

300 

337.8 

156.5 

355 

399.7 

187.2 

410 

461.6 

218,7 

301 

3.38.9 

157.1 

356 

400.8 

187.7 

411 

462.7 

219  3 

302 

340  0 

1.57.6 

357 

401  9 

188.3 

412 

463.8 

219  9 

303 

341.1 

158  2 

358 

403  1 

188  9 

413 

465.0 

220  4 

304 

342  3 

158  7 

359 

401.2 

189.4 

414 

466.1 

221.0 

305 

343  4 

1.59  3 

360 

405  3' 

191  0 

415 

467  2 

221,6 

Vm]  FOODS   Al^ro    FEEDING    STUFFS  109 

56  REDUCING  SUGARS  OTHER  THAN  DEXTROSE. 

Proceed  as  directed  under  54  and  multiply  the  weight  of  dextrose  found  in  55 
by  the  following  factors: 

Levulose,  1.093; 
Invert  sugar,  1.046; 
Arabinose,  0.969; 
Xylose,  1.017; 

Galactose,        1.114. 

Total  Sugars." 
(Applicable  to  cattle  foods.) 

57  preparation  of  solution. 

Place  12  grams  of  the  material  in  a  300  cc.  graduated  flask,  if  the  substance  has  an 
acid  reaction  add  1-3  grams  of  calcium  carbonate,  and  boil  on  a  steam  bath  fori  hour 
with  150  cc.  of  50%  alcohol  by  volume,  using  a  small  funnel  in  the  neck  of  the  flask 
to  condense  the  vapor.  Cool,  and  allow  the  mixture  to  stand  several  hours,  prefer- 
ably overnight.  Make  up  to  volume  with  neutral  95%  alcohol,  mix  thoroughly, 
allow  to  settle,  transfer  200  cc.  to  a  beaker  with  a  pipette,  and  evaporate  on  a  steam 
bath  to  a  volume  of  20-30  cc. 

Do  not  evaporate  to  dryness,  a  little  alcohol  in  the  residue  doing  no  harm.  Trans- 
fer to  a  100  cc.  graduated  flask,  and  rinse  the  beaker  thoroughly  with  water,  adding 
the  rinsings  to  the  contents  of  the  flask.  Add  enough  saturated  neutral  lead  acetate 
solution  to  produce  a  flocculent  precipitate,  shake  thoroughly  and  allow  to  stand  15 
minutes.  Make  up  to  the  mark  with  water,  mix  thorough'y,  and  filter  through  a 
dry  filter.  Add  sufficient  anhydrous  sodium  carbonate  to  the  filtrate  to  precipitate 
all  the  lead,  again  filter  through  a  dry  paper  and  test  the  filtrate  with  a  little  anhy- 
drous sodium  carbonate  to  make  sure  that  all  the  lead  has  been  removed. 

58  determination  of  REDUCING  SUGARS. 

Proceed  as  directed  under  26  or  29-34  respectively,  employing  the  Soxhlet 
modificatiin  of  Fehling's  solution  and  using  25  cc.  of  the  solution  (representing  2 
grams  of  the  sample),  prepared  as  directed  in  57.  Express  the  results  as  dextrose 
or  invert  sugar. 

59  SUCROSE. 

Introduce  50  cc.  of  the  solution,  prepared  as  directed  in  57,  into  a  100  cc.  gradu- 
ated flask,  add  a  piece  of  litmus  paper,  neutralize  with  acetic  acid,  add  5  cc.  of  con- 
centrated hydrochloric  acid  and  allow  the  inversion  to  proceed  at  room  temperature 
as  directed  under  14  or  16.  When  inversi  m  is  complete,  transfer  the  solution  to  a 
beaker,  neutralize  with  sodium  carbonate,  return  the  solution  to  ih^  100  cc.  flask, 
dilute  to  the  mark  with  water,  filter  if  necessary  and  determine  reducing  sugars  in 
50  cc.  of  the  solution  (representing  2  grams  of  the  sample)  as  directed  in  58,  and 
calculate  the  results  as  invert  sugar.  Subtract  the  per  cent  of  reducing  sugars  be- 
fore inversion  from  the  per  cent  of  total  sugar  after  inversion,  both  calculated  as 
invert  sugar,  and  multiply  the  difference  by  0.95  to  obtain  the  per  cent  of  sucrose 
present. 

Since  the  insoluble  material  of  grain  or  cattle  food  occupies  some  space  in  the 
flask  as  originally  made  up,  it  is  necessary  to  correct  for  this  volume.  Results 
of  a  large  number  of  determinations  on  various  materials  have  shown  the  average 
volume  of  12  grams  of  material  to  be  9  cc,  and  therefore  to  obtain  the  true  amount 
of  sugars  present  all  results  must  be  multiplied  by  the  factor  0.97. 


110  METHODS    OF   ANALYSIS  [Chap. 


60  Direct  Acid  Hydrolysis  (Modified  Sachsse  Method). — Official. 

(In  this  method  there  will  be  included  as  starch  the  pentosans  and  other  carbo- 
hydrate bodies  present  which  undergo  hydrolysis  and  conversion  into  reducing 
sugars  on  boiling  with  hydrochloric  acid.) 

Stir  a  quantity  of  the  sample,  representing  2.5-3  grams  of  the  dry  material,  in  a 
beaker  with  50  cc.  of  cold  water  for  an  hour.  Transfer  to  a  filter  and  wash  with 
250  cc.  of  cold  water.  Heat  the  insoluble  residue  for  2^  hours  with  200  cc.  of  water 
and  20  cc.  of  hydrochloric  acid  (sp.  gr.  1.125)  in  a  flask  provided  with  a  reflux  con- 
denser. Cool,  and  nearly  neutralize  with  sodium  hydroxid.  Complete  the  volume 
to  250  cc,  filter,  and  determine  the  dextrose  in  an  aliquot  of  the  filtrate  as  directed 
under  52  or  54.  The  weight  of  the  dextrose  obtained  multiplied  by  0.90  gives  the 
weight  of  starch. 

The  factor  0.9  is  the  theoretical  ratio  between  starch  and  glucose  but,  according 
to  Noyes"  and  other  investigators,  the  factor  0.93  more  nearly  approaches  the  actual 
yield. 

Diastase  Method  with  Subsequent  Acid  Hydrolysis. — Tentative. 

61  REAGENT. 

Malt  extract. — Digest  10  grams  of  fresh,  finely  ground  malt  for  2-3  hours  at  or- 
dinary temperature  with  200  cc.  of  water  and  filter.  Determine  the  amount  of  dex- 
trose in  a  given  quantity  of  the  filtrate  after  boiling  with  acid,  etc.,  as  in  the  starch 
determination,  and  make  the  proper  correction  in  the  subsequent  determination. 

62  DETERMINATION. 

Extract  a  convenient  quantity  of  the  substance  (ground  to  an  impalpable  powder 
and  representing  4-5  grams  of  the  dry  material)  on  a  hardened  filterwith  5  successive 
portions  of  10  cc.  of  ether ;  wash  with  150  cc.  of  10%  alcohol  and  then  with  a  little  strong 
alcohol.  Place  the  residue  in  a  beaker  with  50  cc.  of  water,  immerse  the  beaker  in  boil- 
ing water,  and  stir  constantly  for  15  minutes  or  until  all  the  starch  is  gelatinized ;  cool 
to55°C.,  add  20  cc.  of  malt  extract,  and  maintain  at  this  temperature  for  an  hour. 
Heat  again  to  boiling  for  a  few  minutes,  cool  to55''C.,  add  20  cc.  of  malt  extract,  and 
maintain  at  this  temperature  for  an  hour  or  until  the  residue  treated  with  iodin  shows 
no  blue  color  upon  microscopic  examination.  Cool,  make  up  directly  to  250  cc,  and 
filter.  Place  200  cc.  of  the  filtrate  in  a  flask  with  20  cc.  of  hydrochloric  acid  (sp.  gr. 
1.125) ;  connect  with  a  reflux  condenser  and  heat  in  a  boiling  water  bath  for  2^  hours. 
Cool,  nearly  neutralize  with  sodium  hydroxid  solution,  finish  the  neutralization 
with  sodium  carbonate  solution,  and  make  up  to  500  cc.  Mix  the  solution  well,  pour 
through  a  dry  filter,  and  determine  the  dextrose  in  an  aliquot  as  directed  under 
52  or  54.  Conduct  a  blank  determination  upon  the  same  volume  of  the  malt 
extract  as  used  upon  the  sample  and  correct  the  weight  of  reduced  copper  accord- 
ingly. The  weight  of  the  dextrose  obtained  multiplied  by  0.90  gives  the  weight  of 
starch. 

PENTOSANS.— TENTATIVE. 

63  REAGENT. 

Phloroglucin. — Dissolve  a  small  quantity  of  the  phloroglucin  in  a  few  drops  of 
acetic  anhydrid,  heat  almost  to  boiling,  and  add  a  few  drops  of  concentrated  sul- 


VIII]  FOODS   AND    FEEDING    STUFFS  111 

phuric  acid.  A  violet  color  indicates  the  presence  of  diresorcin.  A  phloroglucin 
which  gives  more  than  a  faint  coloration  may  be  purified  by  the  following  method: 
Heat  in  a  beaker  about  300  cc.  of  hyd  ochloric  acid  (sp.  gr.  1.06)  and  11  grams  of 
commercial  phloroglucin,  added  in  small  quantities  at  a  time,  stirring  constantly 
until  it  has  almost  entirely  dissolved.  Pour  the  hot  solution  into  a  sufficient  quan- 
tity of  the  same  hydrochloric  acid  (cold)  to  make  the  volume  1500  cc.  Allow  it 
to  stand  at  least  overnight,  preferably  several  days,  to  permit  the  diresorcin  to 
crystallize  out.  Filter  immediately  before  using.  A  yellow  tint  does  not  inter- 
fere with  its  usefulness.  In  using  it,  add  the  volume  containing  the  required  amount 
to  the  distillate. 

64  DETERMINATION. 

Place  a  quantity  of  the  material,  2-5  grams,  chosen  so  that  the  weight  of  phloro- 
glucid  obtained  shall  not  exceed  0.300  gram,  in  a  300  cc.  distillation  flask,  together 
with  100  cc.  of  12%  hydrochloric  acid  (sp.  gr.  1.06),  and  several  pieces  of  recently 
heated  pumice  stone.  Place  the  flask  on  a  wire  gauze,  connect  with  a  condenser, 
and  heat,  rather  gently  at  first,  and  regulate  so  as  to  distil  over  30  cc.  in  about  10 
minutes,  the  distillate  passing  through  a  small  filter  paper.  Rep'ace  the  30  cc. 
distilled  by  a  like  quantity  of  the  dilute  acid,  added  by  means  of  a  separatory  funnel 
in  such  a  manner  as  to  wash  down  the  particles  adhering  to  the  sides  of  the  flask,  and 
continue  the  process  until  the  distillate  amounts  to  360  cc.  To  the  total  distillate 
add  gradually  a  quantity  of  phloroglucin  dissolved  in  12%  hydrochloric  acid  and 
stir  thoroughly  the  resulting  mixture.  The  amount  of  phloroglucin  used  should  be 
about  double  that  of  the  furfural  expected.  The  solution  turns  first  yellow,  then 
green,  and  very  soon  an  amorphous  greenish  precipitate  appears,  which  grows 
darker  rapidly,  till  it  becomes  finally  almost  black.  Make  the  solution  up  to  400 
cc.  with  12%  hydrochloric  acid,  and  allow  to  stand  overnight. 

Filter  the  amorphous  black  precipitate  into  a  tared  Gooch  crucible  through  an 
asbestos  mat,  wash  carefully  with  150  cc.  of  water  in  such  a  way  that  the  water  is 
not  entirely  removed  from  the  crucible  until  the  very  last,  then  dry  for  4  hours  at 
the  temperature  of  boiling  water,  cool  and  weigh  in  a  weighing  bottle,  the  increase 
in  weight  being  reckoned  as  furfural  phloroglucid.  To  calculate  the  furfural,  pen- 
tose, or  pentosan  from  the  phloroglucid,  use  the  following  formulas  given  by  Krober: 

(1)  For  a  weight  of  phloroglucid,  designated  by  "a"  in  the  following  formulas, 
under  0.03  gram, 

Furfural  =  (a  +  0.0052)  X  0.5170. 

Pentoses  =  (a  +  0.0052)  X  1.0170. 

Pentosans  =  (a  +  0.0052)  X  0.8949. 

In  the  above  and  also  in  the  following  formulas,  the  factor  0.0052  represents  the 
weight  of  phloroglucid  which  remains  dissolved  in  the  400  cc.  of  acid  solution. 

(2)  For  a  weight  of  phloroglucid  "a"  over  0.300  gram. 

Furfural  =  (a  +  0.0052)  X  0.5180. 

Pentoses  =  (a  +  0.0052)  X  1.0026. 

Pentosans  =  (a  +  0.0052)  X  0.8824. 

For  a  weight  of  phloroglucid  "a"  between  0.03  and  0.300  gram  use  Krober's 
table,  65,  or  the  following  formulas  in  which  the  factors  were  calculated  from 
Krober's  tables  by  C.  A.  Browne,  i' 

Furfural  =  (a  +  0.0052)  X  0.5185. 

Pentoses  =  (a  +  0.0052)  X  1.0075. 

Pentosans  =  (a  +  0.0052)  X  0.8866. 


112 
65 


methods  of  analysis 

Table  8.— Krober's  Table." 

For  Determining  Pentoses  and  Pentosans. 

[Expressed  in  grams.] 


[Chap. 


rORFtlRAL 
PHLOROGLUCID 

FURFURAL 

\RABINOSE 

ARABAN 

XYLOSE 

XYLAN 

PENTOSE 

PENTOSAN 

0.030 

0.0182 

0.0391 

0.0344 

0.0324 

0.0285 

0.0358 

0.0315 

0.031 

0.0188 

0.0402 

0.0354 

0.0333 

0.0293 

0.0368 

0  0324 

0.032 

0.0103 

0.0413 

0.0363 

0.0342 

0.0301 

0.0378 

0.0333 

0.033 

0.0198 

0.0424 

0.0373 

0.0352 

0.0309 

0.0388 

0.0341 

0.034 

0.0203 

0.0435 

0.0383 

0.0361 

0.0317 

0.0398 

0.0350 

0.035 

0.0209 

0.0446 

0.0393 

0.0370 

0.0326 

0.0408 

0.0359 

0.036 

0.0214 

0.0457 

0.0402 

0.0379 

0.0334 

0.0418 

0.0368 

0.037 

0.0219 

0.0468 

0.0412 

0.0388 

0.0342 

0.0428 

0.0377 

0.038 

0.0224 

0.0479 

0.0422 

0.0398 

0.0350 

0.0439 

0.0386 

0.039 

0.0229 

0 .0490 

0.0431 

0.0407 

0.0358 

0.0449 

0.0395 

0.040 

0.0235 

0.0501 

0.0441 

0.0416 

0.0366 

0.0459 

0.0404 

0.041 

0.0240 

0.0512 

0.0451 

0.0425 

0.0374 

0.0469 

0.0413 

0.042 

0.0245 

0.0523 

0.0460 

0.0434 

0.0382 

0.0479 

0.0422 

0.043 

0.0250 

0.0534 

0.0470 

0.0443 

0.0390 

0.0489 

0.0431 

0.044 

0.0255 

0.0545 

0.0480 

0.0452 

0.0398 

0.0499 

0.0440 

0.045 

0.0260 

0.0556 

0.0490 

0.0462 

0.0406 

0.0509 

0.0448 

0.046 

0.0266 

0.0567 

0.0499 

0.0471 

0.0414 

0.0519 

0.0457 

0.047 

0.0271 

0.0578 

0.0509 

0.0480 

0.0422 

0.0529 

0.0466 

0.048 

0.0276 

0.0589 

0.0519 

0.0489 

0.0430 

0.0539 

0.0475 

0.049 

0 .0281 

0.0600 

0.0528 

0.0498 

0.0438 

0.0549 

0.0484 

0.050 

0.0286 

0.0611 

0.0538 

0.0507 

0.0446 

0.0559 

0.0492 

0.051 

0.0292 

0.0622 

0.0548 

0.0516 

0.0454 

0.0569 

0.0501 

0.052 

0.0297 

0.0633 

0.0557 

0.0525 

0.0462 

0.0579 

0.0510 

0.053 

0.0302 

0.0644 

0.0567 

0.0534 

0.0470 

0.0589 

0.0519 

0.054 

0.0307 

0.0655 

0.0576 

0.0543 

0.0478 

0.0599 

0.0528 

0.055 

0.0312 

0.0666 

0.0586 

0.0553 

0.0486 

0.0610 

0.0537 

0.056 

0.0318 

0.0677 

0.0596 

0.0562 

0.0494 

0.0620 

0.0546 

0.057 

0.0323 

0.0688 

0.0605 

0.0571 

0.0502 

0.0630 

0.0555 

0.058 

0.0328 

0.0699 

0.0615 

0.0580 

0  0510 

0.0640 

0.0564 

0.059 

0.0333 

0.0710 

0.0624 

0.0589 

0.0518 

0.0650 

0.0573 

0.060 

0.0338 

0.0721 

0.0634 

0.0598 

0.0526 

0.0660 

0.0581 

0.061 

0.0344 

0.0732 

0.0644 

0.0607 

0.0534 

0.0670 

0.0590 

0.062 

0.0349 

0.0743 

0.0653 

0.0616 

0.0542 

0.0680 

0.0599 

0.063 

0.0354 

0.0754 

0.0663 

0.0626 

0.0550 

0.0690 

0.0608 

0.064 

0.0359 

0.0765 

0.0673 

0.0635 

0.0558 

0.0700 

0.0617 

0.065 

0.0364 

0.0776 

0.0683 

0.0644 

0.0567 

0.0710 

0.0625 

0.066 

0.0370 

0.0787 

0.0692 

0.0653 

0.0575 

0.0720 

0.0634 

0.067 

0.0375 

0.0798 

0.0702 

0.0662 

0.0583 

0.0730 

0.0643 

0.068 

0.0380 

0.0809 

0.0712 

0.0672 

0.0591 

0.0741 

0.0652 

0.069 

0.0385 

0.0820 

0.0721 

0.0681 

0.0599 

0.0751 

0.0661 

0.070 

0.0390 

0.0831 

0.0731 

0.0690 

0.0607 

0.0761 

0.0670 

0.071 

0.0396 

0.0842 

0.0741 

0.0699 

0.0615 

0.0771 

0.0679 

0.072 

0.0401 

0.0S53 

0.0750 

0.0708 

0  0623 

0.0781 

0.0688 

0.073 

0.0406 

0.0864 

0.0760 

0.0717 

0.0631 

0.0791 

0.0697 

0.O74 

0.0411 

0.0875 

0.0770 

0.0726 

0.0639 

0.0801 

0.0706 

VIII] 
65 


FOODS  AND  FEEDING  STUFFS 

Table  8.— Krober's  Table.— Continued. 

(Expressed  in  grams  | 


113 


lURFURAI, 

FURFURAL 

AR.AllINOSE 

AR.^DAN 

XYLOSE 

XYLAN 

PENTOSE 

PENTOSAN 

PHLOROQIUCID 

0.075 

0.0416 

0.0886 

0.0780 

0.0736 

0.0647 

0.0811 

0.0714 

0.076 

0.0422 

0.0S97 

0.0780 

0.0745 

0.0655 

0.0821 

0.0722 

0.077 

0.0427 

0.0908 

0.0799 

0.0754 

0.0G63 

0.0831 

0.0731 

0.078 

0.0432 

0.0019 

0.0809 

0.0763 

0.0671 

0.0841 

0.0740 

0.079 

0.0437 

0.0930 

0.0818 

0.0772 

0.0679 

0.0851 

0.0749 

0.080 

0.0442 

0.0941 

0.0828 

0.0781 

0.0687 

0.0861 

0.0758 

0.081 

0.0448 

0.0952 

0.0838 

0.0790 

0.0695 

0.0871 

0.0767 

0.082 

0.0453 

0.0063 

0.0847 

0.0799 

0.0703 

0.0881 

0.0776 

0.083 

0.0458 

0.0974 

0.0857 

0.0808 

0.0711 

0.0891 

0.0785 

0.084 

0.0463 

0.0985 

0.0867 

0.0817 

0.0719 

0.0901 

0.0794 

0.085 

0.0468 

0.0996 

0.0877 

0.0827 

0.0727 

0.0912 

0.0803 

0.086 

0.0474 

0.1007 

0.0886 

0.0836 

0.0735 

0.0922 

0.0812 

0.087 

0.0479 

0.1018 

0.0896 

0.0845 

0.0743 

0.0932 

0.0821 

0.088 

0.0484 

0.1029 

0.0906 

0.0854 

0.0751 

0.0942 

0.0830 

0.089 

0.0489 

0.1040 

0.0915 

0.0863 

0.0759 

0.0952 

0.0838 

0.090 

0.0494 

0.1051 

0.0925 

0.0872 

0.0767 

0.0962 

0.0847 

0.091 

0.0499 

0.ir62 

0.0935 

0.0881 

0.0775 

0.0972 

0.0856 

0.092 

0.0505 

0.1073 

0.0944 

0.0890 

0.0783 

0.0982 

0.0865 

0.093 

0.0510 

0.1P84 

0.0954 

0.0900 

0.0791 

0.0992 

0.0874 

0.094 

0.0515 

0.1095 

0.0964 

0.0909 

0.0800 

0.1002 

0.0883 

0.095 

0.0520 

0.1106 

0.0974 

0.0918 

0.0808 

0.1012 

0.0891 

0.096 

0.0525 

0.1117 

0.0983 

0.0927 

0.0816 

0.1022 

0.0899 

0.097 

0.0531 

0.1128 

0.0993 

0.0936 

0.0824 

0.1032 

0.0908 

0.098 

0.0536 

0.1139 

0.1003 

0.0946 

0.0832 

0.1043 

0.0917 

0.099 

0.0541 

0.1150 

0.1012 

0.0955 

0.0840 

0.1053 

0.0926 

0.100 

0.0546 

0.1161 

0.1022 

0.0964 

0.0848 

0.1063 

0.0935 

0.101 

0.0551 

0.1171 

0.1032 

0.0973 

0.0856 

0.1073 

0.0944 

0.102 

0.0557 

0.1182 

0.1041 

0.0982 

0.0864 

0.1083 

0.0953 

0.103 

0.0562 

0.1193 

0.1051 

0.0991 

0.0872 

0.1093 

0.0962 

0.104 

0.0567 

0.1204 

0.1060 

0.1000 

0.0880 

0.1103 

0.0971 

0.105 

0.0572 

0.1215 

0.1070 

0.1010 

0.0888 

0.1113 

0.0979 

0.106 

0.0577 

0.1226 

0.1080 

0.1019 

0.0896 

0.1123 

0.0988 

0.107 

0.0582 

0.1237 

0.1089 

0.1028 

0.0904 

0.1133 

0.0997 

0.108 

0.0588 

0.1248 

0.1099 

0.1037 

0.0912 

0.1143 

0.1006 

0.109 

0.0593 

0.1259 

0.1108 

0.1046 

0.0920 

0.1153 

0.1015 

0.110 

0.0598 

0.1270 

0.1118 

0.1055 

0.0028 

0.1163 

0.1023 

0.111 

0.0603 

0.1281 

0.1128 

0.1064 

0.0936 

0.1173 

0.1032 

0.112 

0.0608 

0.1292 

0.1137 

0.1073 

0.0944 

0.11S3 

0.1041 

0.113 

0.0614 

0.1303 

0.1147 

0.1082 

0.0952 

0.1193 

0.1050 

0.114 

0.0619 

0.1314 

0.1156 

0.1091 

0.0960 

0.1203 

0.1059 

0.115 

0.0624 

0.1325 

0.1166 

0.1101 

0.0968 

0.1213 

0.1067 

0.116 

0.0629 

0.1336 

0.1176 

0.1110 

0.0976 

0.1223 

0.1076 

0.117 

0.0634 

0.1347 

0.1185 

0.1119 

0.0984 

0.1233 

0.1085 

0.118 

0.0640 

0,1358 

0.1195 

0.1128 

0.0992 

0.1243 

0.1094 

0.119 

0.0645 

0.1369 

0.1204 

0.1137 

0.1000 

0.1253 

0.1103 

114 


METHODS    OF   ANALYSIS 


[Chap. 


Table  8.— Krober-s  Table.— Continued. 

[Expressed  in  grams.) 


FURFDRAI. 
PHLOROQLUCID 

FURFURAL 

ARABIN08E 

ABABAN 

XYLOSE 

XYLAN 

PENTOSE 

PENTOSAN 

0.120 

0.0650 

0.1380 

0.1214 

0.1146 

0.1008 

0.1263 

0.1111 

0.121 

0.0655 

0.1391 

0.1224 

0.1155 

0.1016 

0.1273 

0.1120 

0.122 

0.0660 

0.1402 

0.1233 

0.1164 

0.1024 

0.1283 

0.1129 

0.123 

0.0665 

0.1413 

0.1243 

0.1173 

0.1032 

0.1293 

0.1138 

0.124 

0.0671 

0.1424 

0.1253 

0.1182 

0.1040 

0.1303 

0.1147 

0.125 

0.0676 

0.1435 

0.1263 

0.1192 

0.1049 

0.1314 

0.1156 

0.126 

0.0681 

0.1446 

0.1272 

0.1201 

0.1057 

0.1324 

0.1165 

0.127 

0.0686 

0.1457 

0.1282 

0.1210 

0.1065 

0.1334 

0.1174 

0.128 

0.0691 

0 .  1468 

0.1292 

0.1219 

0.1073 

0 . 1344 

0.1183 

0.129 

0.0697 

0.1479 

0.1301 

0.1228 

0.1081 

0.1354 

0.1192 

0.130 

0.0702 

1490 

0.1311 

0.1237 

0.1089 

0.1364 

0.1201 

0.131 

0.0707 

0.1501 

0.1321 

0.1246 

0.1097 

0.1374 

0.1210 

0.132 

0.0712 

0.1512 

0.1330 

0.1255 

0.1105 

0.1384 

0.1219 

0.133 

0.0717 

0.1523 

0.1340 

0.1264 

0.1113 

0.1394 

0.1227 

0.134 

0.0723 

0.1534 

0.1350 

0.1273 

0.1121 

0.1404 

0.1236 

0.135 

0.0728 

0.1545 

0.1360 

0.1283 

0.1129 

0.1414 

0.1244 

0.136 

0.0733 

0.1556 

0.1369 

0.1292 

0.1137 

0.1424 

0.1253 

0.137 

0.0738 

0.1567 

0.1379 

0.1301 

0.1145 

0.1434 

0.1262 

0  138 

0.0743 

0.1578 

0.1389 

0.1310 

0.1153 

0.1444 

0.1271 

0.139 

0.0748 

0.1589 

0.1398 

0.1319 

0.1161 

0.1454 

0.1280 

0.140 

0.0754 

0.1600 

0.1408 

0.1328 

0.1169 

0.1464 

0.1288 

0.141 

0.0759 

0.1611 

0.1418 

0.1337 

0.1177 

0.1474 

0 . 1297 

0.142 

0.0764 

0.1622 

0.1427 

0.1346 

0.1185 

0.1484 

0.1306 

0.143 

0.0769 

0.1633 

0.1437 

0.1355 

0.1193 

0.1494 

0.1315 

0.144 

0.0774 

0.1644 

0.1447 

0.1364 

0.1201 

0.1504 

0.1324 

0.145 

0.0780 

0.1655 

0.1457 

0.1374 

0.1209 

0.1515 

0.1333 

0.146 

0.0785 

0.1666 

0.1466 

0.1383 

0.1217 

0.1525 

0.1342 

0.147 

0.0790 

0.1677 

0.1476 

0.1392 

0.1225 

0.1535 

0.1351 

0.148 

0.0795 

0.16.88 

0.1486 

0.1401 

0.1233 

0.1545 

0.1360 

0.149 

0.0800 

0.1699 

0.1495 

0.1410 

0.1241 

0.1555 

0.1369 

0.150 

0.0805 

0.1710 

0.1505 

0.1419 

0.1249 

0.1565 

0.1377 

0.151 

0.0811 

0.1721 

0.1515 

0.1428 

9.1257 

0.1575 

0.1386 

0.152 

0.0816 

0.1732 

0.1524 

0.1437 

0.1265 

0.1585 

0.1395 

0.153 

0.0821 

0.1743 

0.1534 

0.1446 

0.1273 

0.1595 

0.1404 

0.154 

0.0826 

0.1754 

0.1544 

0.1455 

0.1281 

0.1605 

0.1413 

0.155 

0.0831 

0.1765 

0.1554 

0.1465 

0.1289 

0.1615 

0.1421 

0.156 

0.0837 

0.1776 

0.1563 

0.1474 

0.1297 

0.1625 

0.1430 

0.157 

0.0842 

0.1787 

0.1573 

0.1483 

0 . 1305 

0.1635 

0.1439 

0.158 

0.0847 

0.1798 

0.1583 

0.1492 

0.1313 

0.1645 

0.1448 

0.159 

0.0852 

0.1809 

0.1592 

0.1501 

0.1321 

0.1655 

0.1457 

0.160 

0.0857 

0.1820 

0.1602 

0.1510 

0.1329 

0.1665 

0.1465 

0.161 

0.0863 

0.1831 

0.1612 

0.1519 

0.1337 

0.1675 

0.1474 

0.162 

0.0868 

0.1842 

0.1621 

0.1528 

0.1345 

0.1685 

0.1483 

0.163 

0.0873 

0.1853 

0.1631 

0.1537 

0.1353 

0.1695 

0.1492 

0.164 

0.0878 

0.1864 

0.1640 

0.1546 

0.1361 

0.1705 

0.1501 

vm] 

65 


FOODS   AND    FEEDING    STUFFS 


Table  8.— Krober-s  Table. — Continued. 

(Expressed  in  grams.) 


115 


PURFDRA.I, 
PHI-OROOLCCID 

FURFUR.M. 

AR.VBINO.SE 

ARA.BA.N 

XYLOSE 

XTLAN 

pento.se 

PBNTOSAK 

0.165 

0.0883 

0.1S75 

0.1650 

0.1556 

0 . 1369 

0.1716 

0.1510 

0.166 

0.0SS8 

0.1SS6 

0.1660 

0.1565 

0.1377 

0.1726 

0.1519 

0.167 

0.0894 

0.1897 

0.1669 

0.1574 

0.1385 

0.1736 

0.1528 

0.168 

0.0899 

0 .  1908 

0.1679 

0.1583 

0.1393 

0.1746 

0.1537 

0.169 

0.0904 

0.1919 

0.1688 

0.1592 

0.1401 

0.1756 

0.1546 

0.170 

0.0909 

0.1930 

0.1698 

0.1601 

0.1409 

0.1766 

0.1554 

0.171 

0.0914 

0.1941 

0.1708 

0.1610 

0.1417 

0.1776 

0.1563 

0.172 

0.0920 

0.1952 

0.1717 

0.1619 

0.1425 

0.1786 

0.1572 

0.173 

0.0925 

0.1963 

0.1727 

0.1628 

0.1433 

0.1796 

0.1581 

0.174 

0.0930 

0.1974 

0.1736 

0.1637 

0.1441 

0.1806 

0.1590 

0.175 

0.0935 

0.1985 

0.1746 

0.1647 

0.1449 

0.1816 

0.1598 

0.176 

0.0940 

0.1996 

0.1756 

0.1656 

0.1457 

0.1826 

0.1607 

0.177 

0.0946 

0.2007 

0.1765 

0.1665 

0.1465 

0.1836 

0.1616 

0.178 

0.0951 

0.2018 

0.1775 

0.1674 

0.1473 

0 . 1846 

0.1625 

0.179 

0.0956 

0.2029 

0.1784 

0.1683 

0.1481 

0.1856 

0.1634 

0.180 

0.0961 

0.2039 

0.1794 

0.1692 

0.1489 

0.1866 

0.1642 

0.181 

0.0966 

0.2050 

0.1804 

0.1701 

0.1497 

0.1876 

0.1651 

0.182 

0.0971 

0.2061 

0.1813 

0.1710 

0.1505 

0.1886 

0.1660 

0.183 

0.0977 

0.2072 

0.1823 

0.1719 

0.1513 

0.1896 

0.1669 

0.184 

0.0982 

0.2082 

0.1832 

0.1728 

0.1521 

0.1906 

0.1678 

0.185 

0.0987 

0.2093 

0.1842 

0.1738 

0.1529 

0.1916 

0.1686 

0.186 

0.0992 

0.2104 

0.1851 

0.1747 

0.1537 

0.1926 

0.1695 

0.187 

0.0997 

0.2115 

0.1861 

0.1756 

0.1545 

0.1936 

0.1704 

0.188 

0.1003 

0.2126 

0.1870 

0.1765 

0.1553 

0.1946 

0.1712 

0.189 

0.1008 

0.2136 

0.1880 

0.1774 

0.1561 

0.1955 

0.1721 

0.190 

0.1013 

0.2147 

0.1889 

0.1783 

0.1569 

0.1965 

0.1729 

0.191 

0.1018 

0.2158 

0.1899 

0.1792 

0.1577 

0.1975 

0.1738 

0.192 

0.1023 

0.2168 

0.1908 

0.1801 

0.1585 

0.1985 

0.1747 

0.193 

0.1028 

0.2179 

0.1918 

0.1810 

0.1593 

0.1995 

0.1756 

0.194 

0.1034 

0.2190 

0.1927 

0.1819 

0.1601 

0.2005 

0.1764 

0.195 

0 . 1039 

0.2201 

0.1937 

0.1829 

0.1609 

0.2015 

0.1773 

0.196 

0.1044 

0.2212 

0.1946 

0.1838 

0.1617 

0.2025 

0.1782 

0.197 

0 . 1049 

0  2222 

0.1956 

0 . 1847 

0.1625 

0.2035 

0.1791 

0.198 

0.1054 

0^2233 

0.1965 

0.1856 

0.1633 

0.2045 

0.1800 

0.199 

0.1059 

0.2244 

0.1975 

0.1865 

0.1641 

0.2055 

0.1808 

0.200 

0.1065 

0.2255 

0.1984 

0.1874 

0.1649 

0.2065 

0.1817 

0.201 

0.1070 

0.2266 

0.1994 

0.1883 

0.1657 

0.2075 

0.1826 

0.202 

0.1075 

0.2276 

0.2003 

0.1892 

0.1665 

0.2085 

0.1835 

0.203 

0.1080 

0.2287 

0.2013 

0.1901 

0.1673 

0.2095 

0.1844 

0.204 

0.1085 

0.2298 

0.2022 

0.1910 

0.1681 

0.2105 

0.1853 

0.205 

0.1090 

0.2309 

0.2032 

0.1920 

0.1689 

0.2115 

0.1861 

0.206 

0.1096 

0.2320 

0.2041 

0.1929 

0.1697 

0.2125 

0.1869 

0.207 

o.iini 

0.2330 

0.2051 

0.1938 

0.1705 

0.2134 

0.1878 

0.208 

0.1106 

0.2341 

0.2060 

0.1947 

0.1713 

0.2144 

0.1887 

0.209 

0.1111 

0.2352 

0.2069 

0.1956 

0.1721 

0.2154 

0.1896 

116 
65 


METHODS    OF   ANALYSIS 

Table  8.— Krober's  Table.— Continued. 


[Chap. 


[E 

xpres.sed  in 

grams.] 

FURFURAL 
PHLOROGl.UCID 

FURFURAL 

ARABINOSE 

ARABAN 

XYLOSE 

XYLAN 

PENTOSE 

PENTOSAN 

0.210 

0.1116 

0.2363 

0.2079 

0.1965 

0.1729 

0.2164 

0.1904 

0.211 

0.1121 

0.2374 

0.2089 

0.1975 

0.1737 

0.2174 

0.1913 

0.212 

0.1127 

0.2384 

0.2098 

0.1984 

0.1745 

0.2184 

0.1922 

0.213 

0.1132 

0.2395 

0.2108 

0.1993 

0.1753 

0.2194 

0.1931 

0.214 

0.1137 

0.2406 

0.2117 

0.2002 

0.1761 

0.2204 

0.1940 

0.215 

0.1142 

0.2417 

0.2127 

0.2011 

0.1770 

0.2214 

0.1948 

0.216 

0.1147 

0.2428 

0.2136 

0.2020 

0.1778 

0.2224 

0.1957 

0.217 

0.1152 

0.2438 

0.2146 

0.2029 

0.1786 

0.2234 

0.1966 

0.218 

0.1158 

0.2449 

0.2155 

0.2038 

0.1794 

0.2244 

0.1974 

0.219 

0.1163 

0.2460 

0.2165 

0.2047 

0.1802 

0.2254 

0.1983 

0.220 

0.1168 

0.2471 

0.2174 

0.2057 

0.1810 

0.2264 

0.1992 

0.221 

0.1173 

0.2482 

0.2184 

0.2066 

0.1818 

0.2274 

0.2001 

0.222 

0.1178 

0.2492 

0.2193 

0.2075 

0.1826 

0.2284 

0.2010 

0.223 

0.11S3 

0.2503 

0.2203 

0.2084 

0.1834 

0.2294 

0.2019 

0.224 

0.1189 

0.2514 

0.2212 

0.2093 

0.1842 

0.2304 

0.2028 

0.225 

0.1194 

0.2525 

0.2222 

0.2102 

0.1850 

0.2314 

0.2037 

0.226 

0.1199 

0.2536 

0.2232 

0.2111 

0.1858 

0.2324 

0.2046 

0.227 

0.1204 

0.2546 

0.2241 

0.2121 

0.1866 

0.2334 

0.2054 

0.228 

0.1209 

0.2557 

0.2251 

0.2130 

0.1874 

0.2344 

0.2063 

0.229 

0.1214 

0.2568 

0.2260 

0.2139 

0.1882 

0.2354 

0.2072 

0.230 

0.1220 

0.2579 

0.2270 

0.2148 

0.1890 

0.2364 

0.2081 

0.231 

0.1225 

0.2590 

0.2280 

0.2157 

0.1898 

0.2374 

0.2089 

0.232 

0.1230 

0.2600 

0.2289 

0.2166 

0.1906 

0.2383 

0.2097 

0.233 

0.1235 

0.2611 

0.2299 

0.2175 

0.1914 

0.2393 

0.2106 

0.234 

0.1240 

0.2622 

0.2308 

0.2184 

0.1922 

0.2403 

0.2115 

0.235 

0.1245 

0.2633 

0.2318 

0.2193 

0.1930 

0.2413 

0.2124 

0.236 

0.1251 

0.2644 

0.2327 

0.2202 

0.1938 

0.2423 

0.2132 

0.237 

0.1256 

0.2654 

0.2337 

0.2211 

0.1946 

0.2433 

0.2141 

0.238 

0.1261 

0.2665 

0.2346 

0.2220 

0.1954 

0.2443 

0.2150 

0.239 

0.1266 

0.2676 

0.2356 

0.2229 

0.1962 

0.2453 

0.2159 

0.240 

0.1271 

0.2687 

0.2365 

0.2239 

0.1970 

0.2463 

0.2168 

0.241 

0.1276 

0.2698 

0.2375 

0.2248 

0.1978 

0.2473 

0.2176 

0.242 

0.1281 

0.2708 

0.2384 

0.2257 

0.1986 

0.2483 

0.2185 

0.243 

0.1287 

0.2719 

0.2394 

0.2266 

0.1994 

0.2493 

0.2194 

0.244 

0.1292 

0.2730 

0.2403 

0.2275 

0.2002 

0.2503 

0.2203 

0.245 

0.1297 

0.2741 

0.2413 

0.2284 

0.2010 

0.2513 

0.2212 

0.246 

0.1302 

0.2752 

0.2422 

0.2293 

0.2018 

0.2523 

0.2220 

0.247 

0.1307 

0.2762 

0.2432 

0.2302 

0.2026 

0.2533 

0.2229 

0.248 

0.1312 

0.2773 

0.2441 

0.2311 

0.2034 

0.2543 

0.2238 

0.249 

0.1318 

0.2784 

0.2451 

0.2320 

0.2042 

0.2553 

0.2247 

0.250 

0.1323 

0.2795 

0.2460 

0.2330 

0.2050 

0.2563 

0.2256 

0.251 

0.1328 

0.2806 

0.2470 

0.2339 

0.2058 

0.2573 

0.2264 

0.2.52 

0.1333 

0.2816 

0.2479 

0.2348 

0.2066 

0.2582 

0.2272 

0.253 

0.1338 

0.2827 

0.2489 

0.2357 

0.2074 

0.2592 

0.2281 

0.254 

0.1343 

0.2838 

0.2498 

0.2366 

0.2082 

0.2602 

0.2290 

vni] 

65 


FOODS  AND  FEEDING  STUFFS 


Table  8.— Krober's  Table.— Continued. 

[Expressed  in  grams.) 


117 


FURFURAL 
PHLOROQLUCID 

FUBFUR.^L 

ARABIN08E 

ARABAN 

XTLOSE 

XYLAN 

PENTOSE 

PENTOSAN 

0.255 

0.1349 

0.2849 

0.2508 

0.2375 

0.2090 

0.2612 

0.2299 

0.256 

0.13.54 

0.2860 

0.2517 

0.23S4 

0.2098 

0.2622 

0.2317 

0.257 

0.1359 

0.2870 

0.2526 

0.2393 

0.2106 

0.2632 

0.2316 

0.258 

0.1364 

0.2881 

0.2536 

0.2402 

0.2114 

0.2642 

0.2325 

0.259 

0.1369 

0.2892 

0.2545 

0.2411 

0.2122 

0.2652 

0.2334 

0.260 

0.1374 

0.29'}3 

0.2555 

0.2420 

0.2130 

0.2662 

0.2342 

0.261 

0.1380 

0.2914 

0.2565 

0.2429 

0.2138 

0.2672 

0.2351 

0.262 

0.1385 

0.2924 

0.2574 

0.2438 

0.2146 

0.2681 

0.2359 

0.263 

0.1390 

0.2935 

0.2584 

0.2447 

0.2154 

0.2691 

0.2368 

0.264 

0.1395 

0.2946 

0.2593 

0.2456 

0.2162 

0.2701 

0.2377 

0.265 

0.1400 

0.2957 

0.26^3 

0.2465 

0.2170 

0.2711 

0.2385 

0.266 

0.1405 

0.2968 

0.2612 

0.2474 

0.2178 

0.2721 

0.2394 

0.267 

0.1411 

0.2978 

0.2622 

0.2483 

0.2186 

0.2731 

0.2403 

0.26S 

0.1416 

0.2989 

0.2631 

0.2492 

0.2194 

0.2741 

0.2412 

0.269 

0.1421 

0.3000 

0.2641 

0.2502 

0.2202 

0.2751 

0.2421 

0.270 

0.1426 

0.3011 

0.2650 

0.2511 

0.2210 

0.2701 

0.2429 

0.271 

0.1431 

0.3022 

0.2660 

0.2520 

0.2218 

0.2771 

0.2438 

0.272 

0.1436 

0.3932 

0.2669 

0.2529 

0.2226 

0.2781 

0.2447 

0.273 

0.1442 

0.3043 

0.2679 

0.2538 

0.2234 

0.2791 

0.2456 

0.274 

0.1447 

0.3054 

0.2688 

0.2547 

0.2242 

0.2801 

0.2465 

0.275 

0.1452 

0.3065 

0.2698 

0.2556 

0.2250 

0.2811 

0.2473 

0.276 

0.1457 

0.3076 

0.2707 

0.2565 

0.2258 

0.2821 

0.2482 

0.277 

0.1462 

0.3086 

0.2717 

0.2574 

0.2266 

0.2830 

0.2490 

0.278 

0.1467 

0.3097 

0.2726 

0.2583 

0.2274 

0.2840 

0.2499 

0.279 

0.1473 

0.3108 

0.2736 

0.2592 

0.2282 

0.2850 

0.2508 

0.280 

0.1478 

0.3119 

0.2745 

0.2602 

0.2290 

0.2861 

0.2517 

0.281 

0.1483 

0.3130 

0.2755 

0.2611 

0.2298 

0.2871 

0.2526 

0.282 

0.1488 

0.3140 

0.2764 

0.2620 

0.2306 

0.2880 

0.2534 

0.283 

0.1493 

0.3151 

0.2774 

0.2629 

0.2314 

0.2890 

0.2543 

0.284 

0.1498 

0.3162 

0.2783 

0.2638 

0.2322 

0.2900 

0.2552 

0.285 

0.1504 

0.3173 

0.2793 

0.2647 

0.2330 

0.2910 

0.2561 

0.286 

0.1509 

0.3184 

0.2802 

0.2656 

0.2338 

0.2920 

0.2570 

0.287 

0.1514 

0.3194 

0.2812 

0.2665 

0.2346 

0.2930 

0.2578 

0.288 

0.1519 

0.3205 

0.2821 

0.2674 

0.2354 

0.2940 

0.2587 

0.289 

0.1524 

0.3216 

0.2831 

0.2683 

0.2362 

0.2950 

0.2596 

0.290 

0.1529 

0.3227 

0.2840 

0.2693 

0.2370 

0.2960 

0.2605 

0.291 

0.1535 

0.3238 

0.2850 

0.2702 

0.2378 

0.2970 

0.2614 

0.292 

0.1540 

0.3248 

0.2859 

0.2711 

0.2386 

0.2980 

0.2622 

0.293 

0.1545 

0.3259 

0.2868 

0.2720 

0.2394 

0.2990 

0.2631 

0.294 

0.1550 

0.3270 

0.2878 

0.2729 

0.2402 

0.3000 

0.2640 

0.295 

0.1555 

0.3281 

0.2887 

0.2738 

0.2410 

0.3010 

0.2649 

0.296 

0.1560 

0.3292 

0.2897 

0.2747 

0.2418 

0.3020 

0.2658 

0.297 

0.1566 

0.3302 

0.2906 

0.2756 

0.2426 

0.3030 

0.2666 

0.29S 

0.1571 

0.3313 

0.2916 

0.2765 

0.2434 

0.3040 

0.2675 

0.299 

0.1576 

0.3324 

0.2925 

0.2774 

0.2442 

0.3050 

0.2684 

0.300 

0.1581 

0.3335 

0.2935 

0.27S4 

0.2450 

O.P.^'.eX) 

0.2693 

118  METHODS    OF   ANALYSIS  [Chap. 

66  GALACTAN.— TENTATIVE. 

Extract  a  convenient  quantity  of  the  substance,  representing  2.5-3  grams  of  the 
dry  material,  on  a  hardened  filter  with  5  successive  portions  of  10  cc.  of  ether,  place 
the  extracted  residue  in  a  beaker,  about  5.5  cm.  in  diameter  and  7  cm.  deep,  together 
with  60  cc.  of  nitric  acid  of  1.15  sp.  gr.,  and  evaporate  the  solution  to  exactly  one 
third  its  volume  in  a  water  bath  at  a  temperature  of  94°-96°C.  After  standing  24 
hours,  add  10  cc.  of  water  to  the  precipitate,  and  allow  it  to  stand  another  24  hours. 
The  mucic  acid  has  in  the  meantime  crystallized,  but  it  is  mixed  with  considerable 
material  only  partially  oxidized  by  the  nitric  acid.  Filter  the  solution  through  filter 
paper,  wash  with  30  cc.  of  water  to  remove  as  much  of  the  nitric  acid  as  possible, 
and  replace  the  filter  and  contents  in  the  beaker.  Add  30  cc.  of  ammonium  car- 
bonate solution,  consisting  of  1  part  ammonium  carbonate,  19  parts  water,  and  1 
part  strong  ammonium  hydroxid,  and  heat  the  mixture  on  a  water  bath,  at  80°C., 
for  15  minutes,  with  constant  stirring.  The  ammonium  carbonate  takes  up  the 
mucic  acid,  forming  soluble  ammonium  mucate.  Wash  the  filter  paper  and  con- 
tents several  times  with  hot  water  by  decantation,  passing  the  washings  through  a 
filter  paper,  to  which  final' y  transfer  the  material  and  thoroughly  wash.  Evapo- 
rate the  filtrate  to  dryness  over  a  water  bath,  avoiding  unnecessary  heating  which 
causes  decomposition,  add  5  cc.  of  nitric  acid  of  1.15  sp.  gr.,  stir  thoroughly  the 
mi.xture  and  allow  to  stand  for  30  minutes.  The  nitric  acid  decomposes  the  am- 
monium mucate,  precipitating  the  mucic  acid;  collect  this  on  a  tared  filter  or  Gooch, 
wash  with  10-15  cc.  of  water,  then  with  60  cc.  of  alcohol,  and  a  number  of  times 
with  ether,  dry  at  the  temperature  of  boiling  water  for  3  hours,  and  weigh.  Mul- 
tiply the  weight  of  the  mucic  acid  by  1.33,  which  gives  galactose,  and  multiply  this 
product  by  0.9  which  gives  galactan. 

CRUDE  FIBER.-OFFICIAL. 

67  REAGENTS. 

(a)  l.S5%  sulphuric  acid  solution. — Exact  strength,  determined  by  titration. 

(b)  1.25%  sodium  hydroxid  solution. — Exact  strength,  determined  by  titration. 

68  DETERMINATION. 

Extract  a  quantity  of  the  substance,  representing  about  2  grams  of  the  dry 
material,  with  ordinary  ether,  or  use  the  residus  from  the  determination  of  the  ether 
extract.  To  this  residue  in  a  500  cc.  flask  add  200  cc.  of  boiling  1.25%  sulphuric 
acid;  connect  the  flask  with  an  inverted  condenser,  the  tube  of  which  passes  only  a 
short  distance  beyond  the  rubber  stopper  into  the  flask,  or  simply  cover  a  tall  coni- 
cal flask,  which  is  well  suited  for  this  determination,  with  a  watch  glass  or  short 
stemmed  funnel,  boil  at  once  and  cont'nue  boiling  gently  for  30  minutes.  A  blast 
of  air  conducted  nto  the  flask  will  serve  to  reduce  the  frothing  of  the  liquid.  Filter 
through  linen  and  wash  with  boiling  water  until  the  washings  are  no  longer  acid; 
rinse  the  substance  back  into  the  flask  with  200  cc.  of  boiling,  1.25%  solution  of 
sodium  hydroxid,  free  or  nearly  free  from  sodium  carbonate  boil  at  once,  and  con- 
tinue boiling  gently  for  30  minutes  as  directed  above  for  the  treatment  with  acid, 
filter  at  once  rapidly,  and  wash  with  boiling  water  until  the  washings  are  neutral. 
The  last  filtration  may  be  performed  upon  a  Gooch  crucible,  a  linen  filter,  or  a  tared 
filter  paper.  If  a  linen  filter  is  used,  rinse  the  crude  fiber,  after  washing  is  completed, 
into  a  flat-bottomed  platinum  dish  by  means  of  a  jet  of  water;  evaporate  to  dryness 
on  a  steam  bath,  dry  to  constant  weight  at  110°C.,  weigh,  incinerate  completely, 
and  weigh  again.     The  loss  in  weight  is  considered  to  be  crude  fiber.     If  a  tared  filter 


Vin]  FOODS  AND  FEEDING  STUFFS  119 

paper  is  used,  weigh  in  a  weighing  bottle.  In  any  case  the  crude  fiber  after  drying 
to  constant  weight  at  110°C.  must  be  incinerated  and  the  amount  of  the  ash  deducted 
from  the  original  weight. 

69  WATER-SOLUBLE  ACIDITY  OF  FEEDS.— TENTATIVE. 

Weigh  10  grams  of  the  sample  into  a  shaking  bottle,  add  200  cc.  of  water,  and 
shake  for  15  minutes.  Filter  the  extract  through  a  folded  filter  and  take  a  20  cc. 
aliquot  (equivalent  to  1  gram  of  sample)  for  the  titration.  Dilute  with  50  cc.  of 
water  and  titrate  with  N/10  sodium  hydroxid,  using  phenolphthalein  as  indicator. 

In  reporting  the  acidity  of  feeds,  state  the  results  in  terms  of  cc.  of  N/10  sodium 
hydroxid  required  for  neutralization. 

BIBLIOGRAPHY. 

»  Z.  Ver.  Zucker-Ind.,  1900,  37  (I):  357;  1913,  63  (I):  25;  J.  Ind.  Eng.  Chem., 
1913,5:167. 

»  J.  Am.  Chem.  Soc.  1914,  36:  1566. 

»  Ibid.,  1906,  28:  663;  1907,  29:  541. 

«Ibid.,  1902,  24:  1082. 

»  Z.  Rubenzucker-Ind.,  1885,  35  (N.  F.22) :  1012. 

•  Ibid.,  1889,  39  (N.  F.  26) :  734. 

'  Ibid.,  1879,  29  (N.  F.  16) :  1034. 

'  Wein.  Tables  for  the  Quantitative  Estimation  of  the  Sugars.  Translated  by 
Frew.  1896,  p.  26. 

"Ibid.,  p.  33. 

»»  Z.  Rubenzucker-Ind.,  1882,  32  (N.  F.  19) :  606,  865. 
11  U.S.  Bur.  Chem.  Circ.  71. 
"  J.  Am.  Chem.  Soc,  1904.  26:  266. 
"  U.  S.  Bur.  Chem.  Bull.  73,  p.  173. 
"J.  Landw.,  1900,43:379. 


rX.     SACCHARINE  PRODUCTS. 

1  PREPARATION  OF  SAMPLE.-TENTATIVE. 

(a)  Liquids  {molasses,  sirups,  etc.). — Mix  materials  of  this  class  thoroughly. 
If  crystals  of  sugar  are  present,  dissolve  them  either  by  heating  gently  or  by  weigh- 
ing the  whole  mass,  then  adding  water,  heating  until  completely  dissolved  and 
after  cooling,  re-weighing.  Calculate  all  results  to  the  weight  of  the  original 
substance. 

(b)  Semisolids  (jellies,  jams,  etc.). — Weigh  50  grams  of  the  sample  into  a  250 
cc.  graduated  flask.  Treat  with  water,  fill  to  the  mark  and  mix  thoroughly.  If 
insoluble  material  remains,  mix  uniformly  by  shaking  before  taking  aliquots  for 
the  various  determinations. 

(C)  Solids  (sugar,  confectionery,  etc.). — Grind  and  mix  thoroughly  materials 
of  this  class  to  secure  uniform  samples. 

Moisture. 

DRYING  METHODS. 

2  SUGARS.-OFFICIAL. 

Dry  2-5  grams  in  a  flat  dish  (nickel,  platinum,  or  aluminium)  at  the  temperature 
of  boiling  water  for  10  hours;  cool  in  a  desiccator  and  weigh;  then  dry  again  for  an 
hour  or  until  there  is  only  a  slight  change  in  weight. 

With  some  sugars,  more  especially  those  of  large  grain,  there  is  danger  of  occlu- 
sion and  retention  of  water.  The  International  Commission  for  Unifying  Methods 
of  Sugar  Analysis  prescribe  drying  at  105°-110°C.  for  normal  beet  sugars.  This 
temperature  is  sufficient  to  expel  the  last  traces  of  occluded  water  and  is  not  attended 
with  sufficient  decomposition  to  affect  the  weight  of  the  product.  The  drying  tem- 
perature should  never  exceed  110°C^ 

MASSECUITES,  MOLASSES,  AND  OTHER  LIQUID  AND  SEMILIQUID  PRODUCTS. 

3  Drying  upon  Pumice  Stone.— Tentative. 

Prepare  pumice  stone  of  two  grades  of  fineness,  one  of  which  will  pass  through 
a  1  mm.  sieve,  the  other  through  a  6  mm.  sieve.  Make  the  determination  in  flat 
metallic  dishes  or  in  shallow,  flat-bottomed,  weighing  bottles.  Place  a  layer  of 
the  fine  pumice  stone,  3  mm.  in  thickness,  on  the  bottom  of  the  dish,  then  a  layer 
of  the  coarse  pumice  stone  6-10  mm.  in  thickness,  dry  and  weigh.  Dilute  the  sam- 
ple with  a  weighed  portion  of  water  so  that  the  diluted  material  shall  contain  20- 
30%  of  solid  matter.  Weigh  into  the  dish,  prepared  as  described  above,  an  amount 
of  the  diluted  sample  to  yield,  approximately,  1  gram  of  dry  matter.  If  this  weigh- 
ing can  not  be  made  rapidly,  use  a  weighing  bottle  provided  with  a  cork  through 
which  a  pipette  passes.  Dry  in  vacuo  at  70°C.  to  constant  weight,  making  trial 
weighings  at  intervals  of  2  hours.  For  substances  containing  little  or  no  levulose 
or  other  readily  decomposable  substance,  the  drying  may  be  made  in  a  water  oven 
at  the  temperature  of  boiling  water. 

4  Drying  upon  Quartz  Sand.— Tentative. 

Digest  pure  quartz  sand  with  strong  hydrochloric  acid,  wash,  dry,  and  ignite. 
Preserve  in  a  stoppered  bottle. 

121 


122  METHODS    OF   ANALYSIS  [Chap. 

Place  6-7  grams  of  the  prepared  sand  and  a  short  stirring  rod  in  a  flat-bottomed 
dish.  Dry  thoroughly,  cool  in  a  desiccator,  and  weigh.  Then  add  3-4  grams  of 
the  molasses,  mix  with  the  sand  (if  necessary  to  thoroughly  incorporate  the  two, 
add  a  little  water),  dry  in  a  water  oven  at  the  temperature  of  boiling  water 
for  8-10  hours,  stirring  at  intervals  of  an  hour,  cool  in  a  desiccator,  and  weigh. 
Stir,  heat  again  for  an  hour,  cool,  and  weigh.  Repeat  the  heating  and  weighing 
until  the  loss  of  water  in  an  hour  is  not  greater  than  3  mg.  '' 

AREOMETRIC  METHODS. 

(Not  applicable  to  low-grade  sugar  products,  molasses  and  other  materials 
containing  large  amounts  of  non-sugar  solids.) 

SPECIFIC  GRAVITY,  WATER  AND  TOTAL  SOLIDS. 
5  By  Means  of  a  Spindle.— Official. 

The  density  of  juices,  sirups,  etc.,  is  most  conveniently  determined  by  means 
of  the  Brix  hydrometer.  For  rough  work,  or  where  less  accuracy  is  desired,  the 
Baum6  hydrometer  may  be  used.  The  Brix  spindle  should  be  graduated  to  tenths. 
The  range  of  degrees  recorded  by  each  individual  spindle  should  be  as  limited  as 
possible.  The  solution  should  be  as  nearly  as  practicable  of  the  same  tempera- 
ture as  the  air  at  the  time  of  reading,  and,  if  the  variation  from  the  temperature 
of  the  graduation  of  the  spindle  amounts  to  more  than  1°,  a  correction  must  be 
applied  according  to  the  table  under  6.  Before  taking  the  density  of  a  juice,  allow 
it  to  stand  in  the  cylinder  until  all  air  bubbles  have  escaped,  and  until  all  fatty  or 
waxy  matter  has  come  to  the  surface  and  been  skimmed  off.  The  cylinder  should 
be  large  enough  in  diameter  to  allow  the  hydrometer  to  come  to  rest  without  touch- 
ing the  sides.  A  table  of  specific  gravities  at  .. "  and  per  cent  by  weight  of  suc- 
rose is  given  under  9,  and  a  table  for  the  comparison  of  specific  gravities  at  ^^g. ', 
degrees  Brix   (per  cent  by  weight  of  sucrose),  and  degree  Baum6  is  given  under  8. 

If  the  sample  is  too  dense  to  determine  the  density  directly,  dilute  a  weighed 
portion  with  a  weighed  quantity  of  water,  or  dissolve  a  weighed  portion  and  dilute 
to  a  known  volume  with  water. 

In  the  first  instance  the  per  cent  of  total  solids  is  calculated  by  the  following 
formula: 

WS 

Per  cent  of  solids  in  the  undiluted  material  =   —  in  which 

w 

S    =  per  cent  of  solids  in  the  diluted  material; 

W  =  weight  of  the  diluted  material; 

w    =  weight  of  the  sample  taken  for  dilution. 

When  the  dilution  is  made  to  a  definite  volume,  the  following  formula  is  to  be 
used: 

Per  cent  of  solids  in  the  undiluted  material  =     „,     in  which 

W 

V    =  volume  of  the  diluted  solution  at  a  given  temperature; 

D  =  specific  gravity  of  the  diluted  solution  at  the  same  temperature; 

S    =  per  cent  of  solids  in  the  diluted  solution  at  the  same  temperature; 

W  =  weight  of  the  sample  taken  for  dilution  at  the  same  temperature. 

If  the  spindle  reading  be  made  at  any  other  temperature  than  17.5°C.,  the  re- 
sult should  be  corrected  according  to  the  following: 


K] 


SACCHARINE    PRODUCTS 


123 


Table  9. 

For  correction  of  the  readings  of  the  Brix  spindle  when  made  at  other  than  the 
standard  temperature,  17. 5° C. 

(For  temperatures  below  17.5°C.  the  correction  is  to  be  subtracted.) 


TEM- 

DEGREE 

BRIX   OP  THE  SOLUTION 

PERA- 

TORE 

0 

5 

10 

15 

20 

25 

30 

35 

40 

50 

60 

70 

75 

°C. 

0 

0.17 

0.30 

0.41 

0.52 

0.62 

0.72 

0.82 

0.92 

0.98 

1.11 

1.22 

1.25 

1  29 

5 

0.23 

0  30 

0.37 

0.44 

0.52 

0.59 

0.65 

0.72 

0.75 

0.80 

0  88 

0.91 

0  94 

10 

0  20 

0.26 

0.29 

0  33 

0.36 

0.39 

0.42 

0.45 

0.48 

0.50 

0.54 

0.58 

0.61 

n 

0.18 

0.23 

0.26 

0.28 

0.31 

0.34 

0.36 

0.39 

0.41 

0  43 

0.47 

0.50 

0.53 

12 

0  16 

0  20 

0  22 

0.24 

0.26 

0.29 

0.31 

0  33 

0.34 

0.36 

0.40 

0.42 

0.46 

13 

0  14 

0.18 

0  19 

0.21 

0.22 

0.24 

0.26 

0.27 

0.28 

0  29 

0.33 

0.35 

0.39 

14 

0.12 

0  15 

0  16 

0.17 

0.18 

0.19 

0.21 

0.22 

0.22 

0.23 

0.26 

0.28 

0.32 

15 

0.09 

on 

0  12 

0  14 

0.14 

0.15 

0.16 

0.17 

0.16 

0  17 

0.19 

0.21 

0.25 

16 

0.06 

0  07 

0  08 

0.09 

0.10 

0  10 

0.11 

0.12 

0.12 

0.12 

0.14 

0.16 

0.18 

17 

0.02 

0.02 

0.03 

0.03 

0.03 

0.04 

O.W 

0.04 

0.04 

0.04 

0.05 

0.05 

0.06 

18 

0  02 

0.03 

0.03 

0.03 

0  03 

0.03 

0  03 

0  03 

0.03 

0  03 

o.a3 

0.03 

0.02 

19 

0.06 

0  08 

0.08 

0.09 

0.09 

0.10 

0.10 

0.10 

0.10 

0  10 

0.10 

O.OS 

0.06 

20 

0  11 

0.14 

0.15 

0.17 

0.17 

0.18 

0.18 

0.18 

0  19 

0  19 

0.18 

0.15 

0.11 

21 

0.16 

0  20 

0.22 

0.24 

0.24 

0.25 

0.25 

0.25 

0.26 

0.26 

0.25 

0.22 

0.18 

22 

0.21 

0.26 

0.29 

0.31 

0.31 

0.32 

0.32 

0.32 

0.33 

0.34 

0.32 

0.29 

0.25 

23 

0.27 

0.32 

0  35 

0  37 

0.38 

0.39 

0.39 

0.39 

0.40 

0.42 

0.39 

0..36 

0.33 

24 

0  32 

0  38 

0.41 

0.43 

0  44 

0.46 

0.46 

0  47 

0.47 

0.50 

0.46 

0.43 

0.40 

25 

0.37 

0.44 

0.47 

0  49 

0.51 

0.53 

0.54 

0  55- 

0.55 

0  58 

0.54 

0..51 

0.48 

26 

0.43 

0.50 

0.54 

0.56 

0.58 

0.60 

0.61 

0.62 

0  62 

0.66 

0.62 

0..58 

0.55 

27 

0.49 

0.57 

0.61 

0.63 

0.65 

0.68 

0.6S 

0.69 

0  70 

0.74 

0.70 

0.65 

0.62 

28 

0.56 

0.64 

0.68 

0.70 

0.72 

0.76 

0.76 

0.78 

0.78 

0  82 

0.78 

0.72 

0.70 

29 

0.63 

0  71 

0.75 

0.78 

0.79 

0.84 

0.84 

0.86 

0.86 

0.90 

0.86 

0.80 

0.78 

30 

0.70 

0.78 

0,82 

0.87 

0.87 

0.92 

0.92 

0.94 

0.94 

0.98 

0.94 

0.88 

0.86 

35 

1.10 

1.17 

1.22 

1.24 

1.30 

1.32 

1.33 

1.35 

1.36 

1.39 

1..34 

1.27 

1.25 

40 

1.50 

1  61 

1.67 

1.71 

1.73 

1.79 

1.79 

1.80 

1.82 

1.83 

1.78 

1.69 

1.65 

50 

2.65 

2.71 

2.74 

2.78 

2.80 

2.80 

2.80 

2.80 

2.79 

2.70 

2.56 

2.51 

60 

3.87 

3.88 

3  88 

3  88 

3.83 

3.90 

3.82 

3.70 

3.43 

3.41 

70 

5.17 

5.18 

5^20 

5:i4 

5:13 

5.10 

5'08 

5.06 

4.90 

4.72 

4.47 

4.35 

80 

6.62 

6.59 

6.54 

6.46 

6.38 

6.30 

6.26 

6.06 

5.82 

5.50 

5.33 

90 

8.26 

8.16 

8.06 

7.97 

7.83 

7.71 

7.58 

7.30 

6.96 

6.. 58 

6.37 

100 

10.01 

9.87 

9.72 

9.56 

9.39 

9.21 

9.03 

8.64 

8.22 

7.76 

7.42 

Example. — A  sugar  solution  shows  a  reading  of  30.2°  Brix  at  30°C.  To  find  the 
necessary  correction  for  the  conversion  of  this  reading  to  the  reading  which  would 
have  been  obtained  if  the  observation  had  been  made  at  17.5°C.,  find  the  vertical 
column  in  the  table  headed  30°  Brix,  which  is  the  nearest  to  the  observed  reading. 
Follow  down  this  column  until  the  number  is  reached  which  is  opposite  to  the  tem- 
perature of  observation — in  this  case  30°.  The  number  found,  0.92,  is  to  be  added 
to  the  observed  reading. 

7  By  Means  of  a  Pycnometer. — Official. 


(a)  By  specific  gravity  at  —^' — Determine  the  specific  gravity  of  the  solution 

20  °c 
at  -|5-"  by  means  of  a  pycnometer  and  ascertain  the  corresponding  per  cent  by 

weight  of  sucrose  from  9.  When  the  density  of  the  substance  is  too  high  for  a  direct 
determination,  dilute  and  calculate  the  sucrose  content  of  the  original  material  aa 
directed  under  5. 

(b)  By  specific  gravity  at  -jf^' — Proceed  as  directed  under  (a),  the  determina- 

17  5°C  20°C 

tions  of  specific  gravity  being  made  at  -777? '  instead  of  at  -rr^-    Ascertain  the  corre- 


17.5° 

spending  per  cent  by  weight  of  sucrose  from  8. 
The  pycnometer  deternaination  should  not 
20°C. 
17.5°-   "^     -i^' 


made  at  any  other  temperature 


124 
8 


METHODS    OF   ANALYSIS 


For  the  comparison  of  specific  gravities  at 


Table  10. 

17. 5°  C. 


17.5° 
Degree  Baume  =  146.78 


Brix  and 


[Chap. 


Baumi. 


146.78 
sp.gr. 


DEGREE 

DEGREE 

DEGREE 

BHIX  OR 

BRIX  OR 

BBIX  OR 

PER  CENT 

PER  CENT 

PER  CENT 

SPECIFIC 

DEGREE 

SPECIFIC 

DEGREE 

SPECIFIC 

DEGREE 

BY 
WEIGHT 

GRAVITY 

BAUM6 

BY 
WEIGHT 

GRAVITY 

BAUMi 

BY 

WEIGHT 

GRAVITY 

BAUMfi 

or 

OF 

OF 

SUCROSE 

SUCROSE 

SUCROSE 

1.0 

1.00388 

0.6 

33.0 

1.14423 

18.5 

65.0 

1.31989 

35.6 

2.0 

1.00779 

1.1 

34.0 

1.14915  , 

19.05  i 

66.0 

1.32601 

36.1 

3.0 

1.01173 

1.7 

35.0 

1.15411  ! 

19.6 

67.0 

1.33217 

36.6 

4.0 

1.01570 

2.3 

36.0 

1.15911 

20.1     i 

68.0 

1.33836 

37.1 

5.0 

1.01970 

2.8 

37.0 

1.16413 

20.7    i 

69.0 

1.34460 

37.6 

6.0 

1.02373 

3.4 

38.0 

1.16920 

21.2 

70.0 

1.35088 

38.1 

7.0 

1.02779 

4.0 

39.0 

1.17430  1 

21.8 

71.0 

1.35720 

38.6 

8.0 

1.03187 

4.5 

40.0 

1.17943  1 

22.3 

72.0 

1.36355 

39.1 

9.0 

1.03599 

5.1 

41.0 

1.18460  i 

22.9 

73.0 

1.36995 

39.6 

10.0 

1.04014 

5.7 

42.0 

1.18981  1 

23.4 

74.0 

1.37639 

40.1 

11.0 

1.04431 

6.2 

43.0 

1.19505  j 

23.95 

75.0 

1.38287 

40.6 

12.0 

1.04852 

6.8 

44.0 

1.20033  ! 

24.5 

76.0 

1.38939 

41.1 

13.0 

1.05276 

7.4 

45.0 

1.20565 

25.0 

77.0 

1.39595 

41.6 

14.0 

1.05703 

7.9 

46.0 

1.21100  , 

25.6 

78.0 

1.40254 

42.1 

15.0 

1.06133 

8.5 

47.0 

1.21639 

26.1     j 

79.0 

1.40918 

42.6 

16.0 

1.06566 

9.0 

48.0 

1.22182  1 

26.6 

80.0 

1.41586 

43.1 

17.0 

1.07002 

9.6 

49.0 

1.22728 

27.2    I 

81.0 

1.42258 

43.6 

18.0 

1.07441 

10.1 

50.0 

1.23278  1 

27.7    1 

82.0 

1.42934 

44.1 

19.0 

1.07884 

10.7 

51.0 

1.23832  ! 

28.2    i 

83.0 

1.43614 

44.6 

20.0 

1.08329 

11.3 

52.0 

1.24390  i 

28.8  : 

84.0 

1.44298 

45.1 

21.0 

1.08778 

11.8 

53.0 

1.24951  1 

29.3 

85.0 

1.44986 

45.5 

22.0 

1.09231 

12.4 

54.0 

1.25517  j 

29.8 

86.0 

1.45678 

46.0 

23.0 

1.09686 

13.0 

55.0 

1.26086  1 

30.4 

87.0 

1.46374 

46.5 

24.0 

1  .'10145 

13.5 

56.0 

1.26658  1 

30.9 

88.0 

1.47074 

47.0 

25.0 

1.10607 

14.1     i 

57.0 

1.27235 

31.4 

89.0 

1.47778 

47.45 

26.0 

1.11072 

14.6 

58.0 

1.27816 

31.9    ' 

90.0 

1.48486 

47.9 

27.0 

1.11541 

15.2 

59.0 

1.28400  1 

32.5 

91.0 

1.49199 

48.5 

28.0 

1.12013 

15.7 

60.0 

1.28989  , 

33.0 

92.0 

1.49915 

48.9 

29.0 

1.12488 

16.3 

61.0 

1.29581  1 

33.5 

93.0 

1.50635 

49.4 

30.0 

1.12967 

16.8 

62.0 

1.30177  1 

34.0 

94.0 

1.51359 

49.8 

31.0 

1 . 13449 

17.4 

63.0 

1.30777  1 

34.5 

95.0 

1.52087 

50.3 

32.0 

1.13934 

17.95 

64.0 

1.31381  1 

35.1 

When  the  number  expressing  the  specific  gravity  found  by  analysis  falls  between 
the  numbers  given  in  the  above  table,  the  exact  equivalent  in  degrees  Brix  or  Baume 
is  found  by  a  simple  calculation. 

Example. — The  pycnometer  shows  the  specific  gravity  of  a  certain  sirup  to  be 
1.20909.  The  table  shows  that  the  corresponding  degree  Brix  is  between  45.0  and 
46.0.  Subtracting  the  specific  gravity  of  a  solution  of  45°  Brix  from  the  correspond- 
ing figure  for  46°,  we  have  (expressing  the  specific  gravities  as  whole  numbers) 
121,100  —  120,565  =  535,  the  difference  in  specific  gravity  for  1°  Brix  at  this  point 
in  the  table.     Subtracting  the  specific  gravity  corresponding  to  45°  from  the  spe- 

344 
cific  gravity  found  by  analysis,  we  have  120,909  -  120,565  =  344;  -—  =  0.64,  the  frac- 

OoO 

tion  of  1°  Brix  more  than  45°.     The  degree  Brix,  corresponding  to  a  sp.  gr.  of  1.20909, 
is  therefore  45.64. 


IX] 


SACCHARINE    PRODUCTS 


125 


9  Table  11. 

Densities^  of  solutions  of  cane  sugar  at  20°C. 

(This  table  is  the  basis  for  standardizing  hydrometers  indicating  per  cent  of  sugar 

at  20°C.) 


TENTHS  OF  PER  CENT 

PER  CENT 

SUGAR 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

0 

0.998234 

0.998622 

0.999010 

0.999398 

0.999786 

1.000174 

1.000563 

1.000952 

1.001342 

1.001731 

1 

1.002120 

1.002509 

1.002897 

1.003286 

1.003675 

1.004064 

1.004453 

1,004844 

1.005234 

1.005624 

2 

1.006015 

1.006405 

1.00079G 

1.007188 

1. 007580 

1.007972 

1.008363 

1.008755 

1.009148 

1.009541 

3 

1 . 009934 

1.010327 

1.010721 

1.011115 

1.011510 

1.011904 

1.012298 

1.012694 

1.013089 

1,013485 

4 

1.013881 

1.014277 

1.014673 

1.015070 

1.015407 

1.015864 

1.016261 

1.016659 

1.017058 

1,017456 

5 

1.017854 

1.018253 

1.018652 

1.019052 

1.019451 

1.019851 

1.020251 

1.020651 

1,021053 

1,021454 

6 

1.021855 

1.022257 

1.022659 

1.023061 

1.023463 

1.023867 

1.024270 

1.024673 

1.025077 

1,025481 

7 

1.025885 

1.026289 

1.026694 

1.027099 

1.027504 

1,027910 

1.028316 

1.028722 

1.029128 

1,029535 

8 

1.029942 

1.030349 

1.030757 

1.031165 

1.031573 

1.031982 

1.032391 

1.032800 

1.033209 

1,0.33619 

9 

1.034029 

1.034439 

1.034850 

1.035260 

1.035671 

1.036082 

1.036494 

1.036906 

1.037318 

1,037730 

10 

1.038143 

1.038556 

1.038970 

1.039.383 

1.039797 

1.040212 

1. 040626 

1.041041 

1.041456 

1.041872 

11 

1.042288 

1.042704 

1.043121 

1.043537 

1.043954 

1.041370 

1.014788 

1.045206 

1.045625 

1 . 046043 

12 

1,046462 

1.046881 

1.047300 

1.047720 

1.048140 

1.048559 

1.048980 

1.049401 

1.049822 

1.050243 

13 

1.050665 

1.051087 

1.051510 

1.051933 

1.052356 

1.052778 

1.053202 

1.053626 

1.0.54050 

1.054475 

14 

1.054900 

1.055325 

1.055751 

1.056176 

1.056602 

1.057029 

1.057455 

1.057882 

1.058310 

1.058737 

15 

1.059165 

1.059593 

1.060022 

1.060451 

1.060880 

1.061308 

1.061738 

1,062168 

1.062598 

1.063029 

16 

1.063460 

1.063892 

1.064324 

1.064756 

1.065188 

1.065621 

1.066054 

1.066487 

1.066921 

1.067355 

17 

1.067789 

1.068223 

1.068658 

1.069093 

1.069529 

1.069964 

1.070400 

1.070836 

1.071273 

1.071710 

18 

1.072147 

1.072585 

1.073023 

1.073461 

1.073900 

1.074338 

1.074777 

1.075217 

1.075657 

1.076097 

19 

1.076537 

1.076978 

1.077419 

1.077860 

1.078302 

1.078744 

1.079187 

1.079629 

1.080072 

1.080515 

20 

1.0S0959 

1.081403 

1.081848 

1.082292 

1.082737 

1.083182 

1.083628 

1.084074 

1.084520 

1.084967 

21 

1.085414 

1.085861 

1.086309 

1.086757 

1.087205 

1.087652 

1.088101 

1.088550 

1.089000 

1.089450 

22 

1.089900 

1.090351 

1.090802 

1.091253 

1.091704 

1.092155 

1.092607 

1.093060 

1.093513 

1.093966 

23 

1.094420 

1.094874 

1.095328 

1.095782 

1.096236 

1.096691 

1.097147 

1.097603 

1.098058 

1.098514 

24 

1.098971 

1.099428 

1.099886 

1.100344 

1.100802 

1.101259 

1.101718 

1.102177 

1.102637 

1 . 103097 

25 

1.103557 

1.104017 

1 . 104478 

1.104938 

1.105400 

1.105862 

1.106324 

1.106786 

1.107248 

1.107711 

26 

1.108175 

1.108639 

1.109103 

1 . 109568 

1.110033 

1.110497 

1.110963 

1.111429 

1.111895 

1.112361 

27 

1.112828 

1.113295 

1.113763 

1.114229 

1.114697 

1.115166 

1.115635 

1.116104 

1,116572 

1.117042 

28 

1.117512 

1.117982 

1.118453 

1.118923 

1.119395 

1.119867 

1.120339 

1.120812 

1,121284 

1.121757 

29 

1.122231 

1.122705 

1.123179 

1.123653 

1.124128 

1 . 124603 

1.125079 

1.125555 

1,126030 

1.126507 

30 

1.126984 

1.127461 

1.127939 

1.128417 

1.128896 

1.129374 

1,129853 

1.130332 

1.130812 

1.131292 

31 

1.131773 

1.132254 

1.132735 

1.13.3216 

1.133698 

1.134180 

1.134663 

1.135146 

1 . 135628 

1.136112 

32 

1.136596 

1.137080 

1.137565 

1 .  138049 

1.138534 

1.139020 

1.139506 

1 . 139993 

1.140479 

1.140966 

33 

1.141453 

1.141941 

1.142429 

1.142916 

1.143405 

1.143894 

1.144384 

1.144874 

1 . 145363 

1 .  14.5854 

34 

1.146345 

1.146836 

1.147328 

1.147820 

1.148313 

1.148805 

1.149298 

1.149792 

1.150286 

1.150780 

35 

1.151275 

1.151770 

1.152265 

1.152760 

1.153256 

1.153752 

1.154249 

1 . 154746 

1.155242 

1.155740 

36 

1.156238 

1.156736 

1.157235 

1.157733 

1.158233 

1.158733 

1.159233 

1.159733 

1.160233 

1 . 160734 

37 

1.161236 

1.161738 

1.162240 

1.102742 

1.163245 

1.163748 

1.164252 

1.164756 

1.165259 

I . 165764 

38 

1 . 166269 

1.166775 

1.167281 

1.167786 

1.168293 

1.168800 

1.169307 

1.169815 

1.170322 

1.170831 

39 

1.171340 

1.171849 

1.172359 

1.172869 

1.173379 

1.173889 

1.174400 

1.174911 

1.175423 

1.175935 

40 

1.176447 

1.176960 

1.177473 

1.177987 

1.178501 

1.179014 

1.179527 

1.180044 

1 . 180560 

1.181078 

41 

1.1S1592 

1.182108 

1 . 182625 

1.183142 

1.183660 

1.184178 

1.184696 

1.185215 

1 . 185734 

1.186253 

42 

1.186773 

1.187293 

1.187814 

1 . 188335 

1.188856 

1 . 189379 

1.189901 

1.190123 

1.190946 

1.191469 

43 

1.191993 

1.192517 

1.193041 

1.193565 

1 . 194090 

1.194616 

1.195141 

1.195667 

1.196193 

1 . 196720 

44 

1 . 197247 

1.197775 

1.198303 

1.198832 

1.199360 

1.199890 

1.200420 

1.200950 

1.201480 

1.202010 

45 

1.202540 

1.203071 

1.203603 

1.204136 

1.204668 

1.205200 

1.205733 

1.206266 

1.206801 

1.207335 

46 

1.207870 

1.208405 

1.208940 

1.209477 

1.210013 

1.210549 

1.211086 

1.211623 

1.212162 

1.212700 

47 

1.213238 

1.213777 

1.214317 

1.214856 

1.215395 

1.215936 

1.216476 

1.217017 

1.217559 

1.218101 

48 

1.218643 

1.219185 

1.219729 

1.220272 

1.220815 

1.221360 

1.221904 

1.222449 

1.222995 

1.223540 

49 

1.224086 

1.224632 

1.225180 

1.225727 

1.226274 

1.226823 

1.227371 

1.227919 

1.228469 

1.229018 

50 

1.229567 

1.230117 

1.230668 

1.231219 

1.231770 

1.232322 

1.232S74 

1.233426 

1.233979 

1.234532 

51 

1.235085 

1.235639 

1.236194 

1.236748 

1.237303 

1.237859 

1.238414 

1.238970 

1.239527 

1.240084 

52 

1.240641 

1.241198 

1.241757 

1.242315 

1.242873 

1.243433 

1.243992 

1.244552 

1.245113 

1.245673 

53 

1.246234 

1.246795 

1.247358 

1.247920 

1.248482 

1.249046 

1.249609 

1.250172 

1.250737 

1.251301 

54 

1.251866 

1.252431 

1.252997 

1.253563 

1.254129 

1.254697 

1.255264 

1.255831 

1.256400 

1.256967 

55 

1.257535 

1.258104 

1.258674 

1.259244 

1.259815 

1.260385 

1.260955 

1.261527 

1.262099 

1.262671 

56 

1.263243 

1.263816 

1.264390 

1.264963 

1.265537 

1.266112 

1.266686 

1.267261 

1.267837 

1.268413 

57 

1.268989 

1.269565 

1.270143 

1.270720 

1.271299 

1.271877 

1.272455 

1.273035 

1.273614 

1.274194 

58 

1.274774 

1.275354 

1.275936 

1.276517 

1.277098 

1.277680 

1.278262 

1.278844 

1.279428 

1.280011 

59 

1.280595 

1.281179 

1.281764 

1.282349 

1.282935 

1.283521 

1.284107 

1.284694 

1.285281 

1.285869 

126 


METHODS    OF   ANALYSIS 


[Chap. 


Table  11.— Continued. 
Densities  of  solutions  of  cane  sugar  at  20° C. 


TENTHS    OP   PER  CENT 


1.2S6456 
1.292354 
1.298291 
1.304267 
1.310282 

1  316334 
1.322425 
1.328554 
1.334722 
1.341 

1.347174 
1.353456 
1.359778 
1.366139 
1.372536 

1.378971 
1.385446 
1.391956 
1.398505 
1.405091 

1.411715 
1.418374 
1.425072 
1.431807 
1.438579 

1 .445388 
1.452232 
1.459114 
1.466032 
1.472986 

1.479976 
1 .487002 
1.494063 
1.501158 
1.508289 

1.515455 
1.522656 
1.529891 
1.537161 
1.544462 

1.551800 


1.287044 
1.292946 
1.298886 
1.304867 
1.310885 

1.316941 
1.323036 
1.329170 
1.335342 
1.341551 

1.347801 
1.354087 
1.360413 
1.366777 
1.373178 

1.379617 
1.386096 
1.392610 
1.399162 
1.405752 

1.41 

1.419043 

1.425744 

1.432483 

1.439259 

1.446071 
1.452919 
1.459805 
1.466726 
1.473684 

1.480677 
1.487707 
1.494771 
1.501870 
1.509004 

1.516174 
1.523378 
1.530616 
1.537889 
1.545194 


1.287633 
1.293539 
1.299483 
1.305467 
1.3114S9 

1.317549 
1.323648 
1.329785 
1.335961 
1.342174 

1.348427 
1.35471 
1.36104 
1.367415 
1.373820 

1.380262 

1.386745 

1.393263 

1.39! 

1.406412 

1.413044 
1.419711 
1.426416 
1.433158 


1.446754 
1.453605 
1.460495 
1.467420 
1.474381 

1.481378 
1.488411 
1.4954? 
1.50258; 
1.509720 

1.516893 
1.524100 
1.531342 
1.538618 
1.5459: 


1.288222 
1.294131 
1.300079 
1.306068 
1.312093 

1.318157 
1.324259 
1.330401 
1.336581 
1.342798 

1.319055 

1.355349 

1.361682 

1.36: 

1.374463 

1.380909 
1.387396 
1.393917 
1.400477 
1.407074 

1.413709 

1.420380 

1.42 

1.433835 

1.440619 

1.447438 
1.454292 
1.461186 
1.468115 
1.475080 

1.482080 
1.489117 
1.496188 
1.503293 
1.510435 

1.517612 
1.524823 
1.5.32068 
1.539347 
1.543659 


1.289401 
1.295318 
1.301274 
1.307271 
1.313304 

1.319374 
1.325484 
1.331633 
1.337821 
1.344046 

1.350311 
1.356612 
1.362953 
1.36! 
1 .375749 

1.382203 
1.388696 
1.395226 
1.401793 
1.408398 


1.455668 
1.462568 
1.469504 
1.476477 

1.4834S4 
1.490528 
1.497606 
1.504719 
1.511868 

1.519051 
1.526269 
1.5335: 


1.319983 

1.32( 

1.332250 

1.338441 

1.344671 


1.382851 
1.389347 
1.395881 
1.402452 
1.409061 

1.415706 
1.422390 
1.429109 
1.435866 
1.442661 

1.449491 
1.456357 
1.463260 
1  470200 
1.477176 

1.484187 
1.491234 
1.498316 
1.505432 
1.512585 


1.351568 
1.357877 
1.364226 
1.370613 
1.377036 

1.383499 
1.389999 
1.390536 
1.403111 
1.409723 

1.416373 
1.423059 
1.429782 
1.436543 
1.443342 

1.450175 

1.457045 

1.463953 

1.47( 

1.477876 


1.520492 
1.527717 
1.534976 
1.542267 
1.549595 


1.291172 
1.297100 
1.303068 
1.309077 
1.315121 

1.321203 
1.327325 
1.333485 
1.339684 
1.345922 

1.352197 
1.35851 
1.364864 
1.371254 
1.377680 

1.384148 
1.390651 
1 .397192 
1.403771 
1.410387 

1.417039 
1.423730 
1.430457 
1.437222 
1.444024 

1.450860 
1.457735 
1.464645 
1.471592 
1.478575 

1.485593 
1.49264 
1.49973 
1.506859 
1.514019 

1.521212 
1.528441 
1.535704 
1.542998 
1.550329 


1.352827 
1.359144 
1.365501 
1.371894 
1.378326 

1.384796 
1.391303 
1.397848 
1.404430 
1.411051 

1.417707 
1.424400 
1.431131 
1.437900 
1.444705 

1.451545 
1.458424 
1.465338 
1.472289 
1.479275 

1.486297 
1.493355 
1.500447 
1.507574 
1.514737 


10 


REFRACTOMETER  METHOD.— TENT  A  TIVE. 


Determine  the  refractive  index  of  the  solution  at  28°C.  and  obtain  the  corre- 
sponding percentage  of  dry  substance  from  11.  If  the  refractive  index  is  obtained 
at  a  temperature  other  than  28°C.,  correct  the  result  as  indicated  in  12.  If  the 
solution  is  too  dark  to  be  read  in  the  instrument,  dilute  with  a  concentrated  sugar 
solution.  Water  should  never  be  used  for  this  purpose.  Mix  weighed  amounts 
of  the  solution  under  examination  and  a  solution  of  pure  sugar  of  about  the  same 
strength,  and  obtain  the  amount  of  dry  substance  in  the  former  by  the  following 
formula: 


m 


SACCHARINE    PRODUCTS 


127 


(A  +  B)  C  -  BD 


in  which 


X    =  per  cent  of  dry  substance  to  be  found; 

A    =  weight  in  grams  of  the  material  mixed  with  B; 

B    =  weight  in  grams  of  pure  sugar  solution  employed  in  the  dilution; 

C    =  per  cent  of  dry  substance  in  the  mixture  of  A  and  B  obtained  from  the 

refractive  index; 
D  =  per  cent  of  dry  substance  in  the  pure  sugar  solution  obtained  from  its 
refractive  index. 

11  Table  12.— Geerligs''  Table. 

For  dry  substance  in  sugar-house  products  by  the  Abbe  ref Tactometer,  at  28°C. 


INDEX 

PER 
CENT 
DRY 

DECIMALS  TO  BE 
ADDED  FOR 

INDEX 

PER 
CENT 
DRY 

DECIMALS  TO  BE 
ADDED  FOR 

INDEX 

PER 
CENT 
DRY 

DECIMALS  TT  BE 
ADHED  FOR 

SUB- 
STANCE 

FR.\CTIONAL 

READINGS* 

80B- 
.STANCB 

FRACTIONAL 
READINl^S* 

SUB- 
STANCE 

FRACTIONAL 
READINOS* 

1.3335 

1 

0.0001  =  0.05 

1.3484 

11 

0   0001  =  0.05 

1.3746 

27 

0  0001  -  0  05 

1.3349 
1.3364 

2 
3 

0  0002  =  0  1 
0.0003  =  0.2 
0  0001  =  0.25 

1.3500 
1.3516 

12 
13 

0  0002  =  0  1 
0.0003  =  0.2 
0  0004  =  0.25 

1.3764 
1.3782 

28 
29 

0  0002  =  0  1 
0.0003  =  0.15 
0  0004  =  0.2 

1.3379 

4 

0.0005  =  0.3 

1.3530 

14 

0.0005  =  0.3 

1.3800 

30 

0.0005  =  0  25 

1.3394 
1.3409 

5 
6 

0  000fi  =  0.4 
0.0007  =  0.5 
0  OUOS  =  0  6 

1.3546 
1.3562 

15 
16 

0  0006  =  0.4 
0.0007  =  0.45 
0.0008  =  0.5 

1.3818 
1.3836 

31 
32 

0  0006  =  0.3 
0  0007  =  0  35 
0.0008=0  4 

1.3424 

7 

0  0009  =  0,7 

1.3578 

17 

0.0009  =  0.6 

1.3854 

33 

0.0009  =  0.45 

1.3439 
1.3454 

8 
9 

0.0010  =  0  75 
0.0011  =  0.8 
0  0012  =  0  8 

1.3594 
1.3611 

18 
19 

0  0010  =  0.65 
0.0011  =  0.7 
0.0012  =  0.75 

1.3872 
1.3890 

34 
35 

0.0010=0  5 
0.0011  =  0  55 
0  0012  =  06 

1.3469 

10 

0  0013  =  0  85 

1.3627 

20 

0  0013  =  0.8 

1.3909 

36 

0  0013  =  0.65 

0.0014  =  0  9 
00015=  1.0 

1.3644 
1.3661 

21 

22 

0.0014  =  0.85 
0  0015  =  09 
0.0016=0.95 

1.3928 
1.3947 

37 
38 

0  0014  =  0  7 
0  (015  =  0.75 
0  '016  =  0  8 

1.3678 

23 

1.3966 

39 

0  0017  =  0  85 

1.3695 
1.3712 

24 
25 

1.3984 
1.4003 

40 
41 

0  0018  =  09 
0  0019  =  0  95 
0.0020  =  1  0 

1.3729 

26 

0.0^v21=  10 

1.4023 

42 

0.0  01  =  0  05 

1.4292 

55 

0.0001  =  0.05 

1.4711 

73 

0  0001  =  0  0 

1.4043 
1.4063 

43 
44 

0  0002  =  0.1 
0.0003  =  0.15 
0.0004=  0  2 

1.4314 
1.4337 

56 
57 

0  0002  =  0  1 
0  0003  =  0  1 
0  0004  =  0  15 

1.4736 
1.4761 

74 
75 

0.0002  =  0  05 
0.0003  =  0  1 
0  0004  =  0  15 

1.4083 

45 

0  0005  =  0  25 

1.4359 

58 

0  0005  =  0  2 

1.4786 

76 

0  0005=0.2 

1.4104 
1.4124 

46 

47 

0  0006=  0.3 
0.0007=  0  35 
O.OOOS  =  04 

1.4382 
1.4405 

59 
60 

0.0006  =  0  25 
0  0007  =  0  3 
0.0008  =  0  35 

1.4811 
1.4836 

77 
78 

0  0006  =02 
0.0007  =  0  25 
0  OOOS  =  03 

1.4145 

48 

0.0009  =  0  45 

1.4428 

61 

0.0009  =  0  4 

1.4862 

79 

0  0009  =  0.35 

1.4166 
1.4186 

49 
50 

0  0010  =  05 
0  0011  =  0  55 
0  0012  =  0  0 

1.4451 
1.4474 

62 
63 

0  0010  =  0.45 

0  onii  =  05 

0  0012  =  0.5 

1.4888 
1.4914 

80 

81 

0  0010  =  0  35 
00011  =  0  4 
0  0012  =  0  45 

1.4207 

51 

0.0013  =  0  65 

1.4497 

64 

0  0.il3  =  0  55 

1.4940 

82 

0  oon  =  05 

1.4228 
1.4249 

52 
53 

0  0014  =  0  7 
0  0015  =  0  75 
0.0016=  08 

1.4520 
1.4543 

65 
66 

0  0014  =  06 
0  0015  =  0  65 
0  0016  =  0  7 

1.4966 
1.4992 

83 

84 

0  0014  =  05 
0  0015  =  0  55 
0  0016  =  06 

1.4270 

54 

0.0017  =  0  85 

1.4567 

67 

0  0017  =  0  75 

1.5019 

85 

0  0017  =  0  65 

0  0018  =  0  9 

1.4591 

68 

0.0018  =  0  8 

1  5046 

86 

0  0018  =  0  65 

0  0019  =  0.95 
0  0020  =  1  0 

1.4615 

69 

0  0019  =  0  85 
0  0020  =  09 

1.5073 

87 

0  0019=  0  7 
0  0020  =  0  75 

0.0021  =  1.0 

1.4639 

70 

0  0021  =  0.9 

1.5100 

88 

0  0021  =08 

1.4663 

71 

0.0022  =  0.95 

1  5127 

89 

0  0022  =  08 

1.4687 

72 

0  0023=  10 
0.0024=  1.0 

1.5155 

90 

0  0023  =  0.85 
0  0024  =  09 
0  0025  =  0  9 
0  0026=  0  95 
0  0027=  10 
0  0028=  10 

*Find  in  the  table  the  refractive  index  which  is  next  lower  than  the  reading  actu- 
ally made  and  note  the  corresponding  whole  number  for  the  per  cent  of  dry  substance 
Subtract  the  refractive  index  obtainod  from  the  table  from  the  observed  reading; 
the  decimal  corresponding  to  this  difference,  as  given  in  the  column  so  marked,  is 
added  to  the  whole  per  cent  of  dry  substance  as  first  obtained. 


128 
12 


METHODS    OF   ANALYSIS 

Table  13. 
Corrections  for  temperature. 


[Chap. 


DRV   SUBSTANCE 

T0RE  OF 

THE 

0 

5 

10 

15 

20 

25 

30 

40 

50 

60 

70 

80 

90 

PRISMS  IN 

"C. 

Subtract 

- 

20 

0.53 

0.54 

0.55 

0.56 

0.57 

0.58 

0.60 

0.62 

0.64 

0.62 

0.61 

0.60 

0.58 

21 

0.46 

0.47 

0.48 

0.49 

0.50 

0.51 

0.52 

0.54 

0.56 

0.54 

0.53 

0.52 

0.50 

22 

0.40 

0.41 

0.42 

0.42 

0.43 

0.44 

0.45 

0.47 

0.48 

0.47 

0.46 

0.45 

0.44 

23 

0.33 

0.33 

0.34 

0.35 

0.36 

0.37 

0.38 

0.39 

0.40 

0.39 

0.38 

0.38 

0.38 

24 

0.26 

0.26 

0.27 

0.28 

0.28 

0.29 

0.30 

0.31 

0.32 

0.31 

0.31 

0.30 

0.30 

25 

0,20 

0.20 

0.21 

0.21 

0  22 

0.22 

0.23 

0.23 

0.24 

0.23 

0.23 

0.23 

0.22 

26 

0.12 

0.12 

0.13 

0.14 

0.14 

0.15 

0.15 

O.IP 

0.16 

0.16 

0.15 

0.15 

0.14 

27 

0.07 

0.07 

0.07 

0.07 

0.07 

0.07 

0.0? 

0.08 

0.08 

0.08 

0.08 

0.08 

0.07 

Add- 

29 

0.07 

0.07 

0.07 

0.07 

0.07 

0.07 

0.08 

0.08 

0.08 

0.08 

0.08 

0.08 

0.07 

30 

0.12 

0.12 

0.13 

0.14 

0.14 

0.14 

0.15 

0.15 

0.16 

0.16 

0.16 

0.15 

0.14 

31 

0.20 

0.20 

0.21 

0.21 

0.22 

0.22 

0.23 

0.23 

0.24 

0.23 

0.23 

0.23 

0.22 

32 

0.26 

0.26 

0.27 

0.28 

0.28 

0.29 

0.30 

0.31 

0.32 

0.31 

0.31 

0.30 

0.30 

33 

0.33 

0.33 

0.34 

0.35 

0.36 

0.37 

0.38 

0.39 

0.40 

0.39 

0.38 

0.38 

0.38 

34 

0.40 

0.41 

0.42 

0.42 

0.43 

0.44 

0.45 

0.47 

0.48 

0.47 

0.46 

0.45 

0.44 

35 

0.46 

0.47 

0.48 

0.49 

0.50 

0.51 

0.52 

0.54 

0.56 

0.54 

0.53 

0.52 

0.50 

13 


Method  I.— Official. 


Heat  5-10  grams  of  the  sample  in  a  50-100  cc.  platinum  dish  at  100°C.  until  the 
water  is  expelled,  add  a  few  drops  of  pure  olive  oil,  and  heat  slowly  over  a  flame 
until  swelling  ceases.  Then  place  the  dish  in  a  muffle  and  heat  at  low  redness  until 
a  white  ash  is  obtained. 


14 


Method  II.— Official. 


Carbonize  the  mass  at  a  low  heat,  dissolve  the  soluble  salts  in  hot  water,  burn 
the  residual  mass  as  directed  in  13,  add  the  solution  of  soluble  salts,  and  evaporate 
to  dryness  at  100°C.,  ignite  gently,  cool  in  a  desiccator,  and  weigh. 

1 5  Method  III.— Official. 

Saturate  the  sample  with  sulphuric  acid,  dry,  ignite  gently,  then  burn  in  a  muf- 
fle at  low  redness.  Deduct  one  tenth  of  the  weight  of  the  ash,  and  calculate  the 
per  cent. 

1  6  QUANTITATIVE  ANALYSIS  OF  THE  ASH.— OFFICIAL. 

Proceed  as  directed  under  III. 

1  7  SOLUBLE  AND  INSOLUBLE  ASH.— TENTATIVE. 

Ash  the  material  as  directed  under  13  or  14.  Add  water  to  the  ash  in  the  plati- 
num dish,  heat  nearly  to  boiling,  filter  through  an  ashless  filter  paper,  and  wash 
with  hot  water  until  the  combined  filtrate  and  washings  measure  about  60  cc.     Re 


IX]  SACCHARINE    PRODUCTS  129 

turn  the  filter  paper  and  contents  to  the  platinum  dish,  ignite  carefully,  and  weigh. 
Calculate  the  percentages  of  water-soluble  and  water-insoluble  ash. 

1 8  ALKALINITY  OF  THE  SOLUBLE  ASH.-TENTATIVE, 

Cool  the  filtrate  from  1 7  and  titrate  with  N/10  hydrochloric  acid,  using  methyl 
orange  as  an  indicator. 

Express  the  alkalinity  in  terms  of  the  number  of  cc.  of  N/10  acid  per  1  gram  of 
the  sample. 

19  ALKALINITY  OF  THE  INSOLUBLE  ASH.-TENTATIVE. 

Add  an  excess  of  N/10  hydrochloric  acid  (usually  10-15  cc.)  to  the  ignited  insolu- 
ble ash  in  the  platinum  dish,  under  1 7,  heat  to  boiling  over  an  asbestos  plate,  cool, 
and  titrate  the  excess  of  hydrochloric  acid  with  N/10  sodium  hydroxid,  using  methyl 
orange  as  an  indicator. 

Express  the  alkalinity  in  terms  of  the  number  of  cc.  of  N/10  acid  per  1  gram  of 
the  sample. 

20  MINERAL  ADULTERANTS  IN  THE  ASH.-TENTATIVE. 

Mix  100  grams  of  molasses,  sirup,  honey,  or  the  confectionery  solution  prepared 
as  directed  under  1  (b)  and  evaporate  to  a  sirupy  consistency,  with  about  35  grams 
of  concentrated  sulphuric  acid  in  a  large  porcelain  evaporating  dish.  Pass  an 
electric  current  through  it  while  stirring  by  placing  one  platinum  electrode  in  the 
bottom  of  the  dish  near  one  side  and  attaching  the  other  to  the  lower  end  of  the 
glass  rod  with  which  the  contents  are  stirred.  Begin  with  a  current  of  about  1 
ampere  and  graduallj'-  increase  to  4  (modified  from  method  of  Budde  and  Schou* 
for  determining  nitrogen  electrolytically).  In  10-15  minutes  the  mass  is  reduced 
to  a  fine  dry  char,  which  may  be  readily  burnt  to  a  white  ash  in  the  original  dish 
over  a  free  flame  or  in  a  muffle. 

This  method^  is  preferred  to  the  ordinary  method  of  heating  with  sulphuric  acid, 
especially  in  the  case  of  molasses,  because,  if  properly  manipulated,  it  comes  quietly 
into  the  form  of  a  very  finely  divided  char  or  powder,  especially  adapted  for  subse- 
quent quick  ignition. 

If  an  electric  current  is  not  available,  treat  in  a  large  porcelain  dish  100  grams  of 
the  saccharine  solution,  evaporated  to  a  sirupy  consistency,  with  suflBcient  concen- 
trated sulphuric  acid  to  thoroughly  carbonize  the  mass  and  ignite  in  the  usual 
manner. 

The  following  adulterants  may  be  present:  salts  of  tin,  used  in  molasses  to  bleach; 
mineral  pigments,  such  as  chromate  of  lead  in  yellow  confectionery;  oxid  of  iron, 
sometimes  used  to  simulate  the  color  of  chocolate;  and  copper.  These  elements 
may  be  detected  by  the  usual  qualitative  tests. 

21  NITROGEN.— TENTATIVE. 

Determine  nitrogen  in  5  grams  of  the  material  as  directed  under  I,  18,  21  or  23, 
using  a  larger  quantity  of  the  sulphuric  acid  if  necessary  for  complete  digestion. 

SUCROSE. 

22  Method  I.— Tentative. 

(Substances  in  which  the  volume  of  the  combined  insoluble  matter  and  precipitate 
from  clarifying  agents  is  less  than  1  cc.  from  26  grams.) 

Determine  sucrose  by  polarization  before  and  after  inversion,  as  directed  under 
VIII.  14. 


130  METHODS   OF   ANALYSIS  [Chap. 

All  products  which  contain  dextrose  or  other  reducing  sugars  in  the  crystalline 
form,  or  in  supersaturated  solution,  exhibit  the  phenomenon  of  birotation.  The  con- 
stant rotation  only  should  be  employed  in  the  Clerget  formula,  and  to  obtain  this 
the  solutions  prepared  for  direct  polarization  should  be  allowed  to  stand  overnight 
before  making  the  reading.  If  it  is  desired  to  make  the  direct  reading  immediately, 
the  birotation  may  be  destroyed  by  heating  the  neutral  solution  to  boiling  for  a  few 
minutes  or  by  adding  a  few  drops  of  strong  ammonium  hydroxid  before  completing 
the  volume. 

23  Method  II.     {Double  dilution  method.^)— Tentative. 

(Substances  in  which  the  volume  of  the  combined  insoluble  matter  and 
precipitate  from  clarifying  agents  is  more  than  1  cc.  from  26  grams.) 

Weigh  out  a  half  normal  weight  of  the  sample  and  make  up  the  solution  to  100 
cc,  employing  the  appropriate  clarifier  (basic  lead  acetate  for  dark  colored  con- 
fectionery or  molasses  and  alumina  cream  for  light  colored  confectionery).  Also 
weigh  out  a  normal  weight  of  the  sample  and  make  up  a  second  solution  with  the 
clarifier  to  100  cc.  Filter  and  obtain  direct  polariscopic  readings  of  both  solu- 
tions.    Invert  each  solution  as  directed  in  22  and  obtain  its  invert  reading. 

The  true  direct  polarization  of  the  sample  is  the  product  of  the  two  direct  read- 
ings divided  by  their  difference. 

The  true  invert  polarization  is  the  product  of  the  two  invert  readings  divided 
by  their  difference. 

Calculate  the  sucrose  from  the  true  polarizations  thus  obtained  by  the  formula 
given  under  VIII,  14. 

COMMERCIAL  GLUCOSE  (APPROXIMATE). 

24  Method  I— Tentative. 

(Substances  containing  little  or  no  invert  sugar.) 

Commercial  glucose  can  not  be  determined  accurately  owing  to  the  varying 
amounts  of  dextrin,  maltose,  and  dextrose  present  in  this  product.  However,  in 
sirups,  in  which  the  amount  of  invert  sugar  is  so  small  as  not  to  appreciably  affect 
the  result,  commercial  glucose  may  be  estimated  approximately  by  the  following 
formula:^ 

^        (a  -  S)  100  .       ,  .  , 

G  =  in  which 

175 

G  =  per  cent  of  commercial  glucose; 

a    =  direct  polarization; 

S    =  per  cent  of  cane  sugar. 

Express  the  results  in  terms  of  commercial  glucose  polarizing  +175°V. 

Method  II. — Tentative. 

25  (Substances  containing  invert  sugar.') 

Prepare  an  inverted  half  normal  solution  of  the  substance  as  directed  under 
VIII,  14  except  that  after  inversion  cool  the  solution,  make  neutral  to  phenol- 
phthalein  with  sodium  hydroxid  solution,  slightly  acidify  with  hydrochloric  acid, 
and  treat  with  5-10  cc.  of  alumina  cream  before  making  up  to  the  mark.  Filter 
and  polarize  at  87°C.  in  a  200  mm.  jacketed  tube.  Multiply  the  reading  by  200  and 
divide  by  the  factor  103  to  express  the  amount  of  glucose  present  in  terms  of  glu- 
cose polarizing  +175°V. 


IXl  SACCHARINE  PRODUCTS  131 

26  REDUCING  SUGARS.— TENTATIVE. 

Determine  either  as  dextrose  or  invert  sugar  as  directed  under  VIII,  50,  51, 

52,  54,  or  21,  23,  25,  36  or  39. 

27  STARCH.-TENTATIVE. 

Measure  25  cc.  of  a  solution  or  uniform  mixture,  prepared  as  directed  in  1  (b), 
(representing  5  grams  of  the  sample)  into  a  300  cc.  beaker,  or  introduce  5  grams  of 
the  finely  ground  sample  (previously  extracted  with  ether  if  the  sample  contains 
much  fat)  into  the  beaker,  add  sufficient  water  to  make  the  volume  100  cc,  heat 
to  about  60°C.  (avoiding  if  possible  gelatinizing  the  starch)  and  allow  to  stand 
for  about  an  hour,  stirring  frequently  to  secure  complete  solution  of  the  sugars. 
Transfer  to  a  stout  wide-mouthed  bottle,  rinse  the  beaker  with  a  little  warm  water, 
cool,  add  an  equal  volume  of  95%  alcohol,  mix,  and  allow  to  stand  at  least  an  hour. 
Centrifugalize  until  the  precipitate  is  closely  packed  on  the  bottom  of  the  bottle 
and  decant  the  supernatant  liquid  through  a  hardened  filter.  Wash  the  precipi- 
tate with  successive  50  cc.  portions  of  50%  alcohol  by  centrifugalizing  and  decant- 
ing through  the  filter  until  3  or  4  drops  of  the  washings  give  no  test  for  sugar  with 
alphanaphthol  as  described  under  68.  Transfer  the  residue  from  the  bottle  and 
the  hardened  filter  to  a  large  flask  and  determine  starch  as  directed  under  VIII, 

60. 

ETHER  EXTRACT  IN  CONFECTIONERY. 

28  Continuous  Extraction. — Tentative. 

(1)  Measure  25  cc.  of  a  20%  mixture  or  solution,  prepared  as  directed  under  1 
(b),  intoa  very  thin,  readily  frangible,  glass  evaporating  shell  {Hofmeister  Schalchen), 
containing  5-7  grams  of  freshly  ignited  asbestos  fiber;  or  (2)  If  impossible  to  ob- 
tain a  uniform  sample,  weigh  5  grams  of  the  mixed  finely  divided  sample  into  a 
dish,  and  wash  with  water  upon  the  asbestos  in  the  evaporating  shell,  using,  if  neces- 
sary, a  small  portion  of  the  asbestos  fiber  on  a  stirring  rod  to  transfer  the  last  traces 
of  the  sample  from  the  dish  to  the  shell.  Dry  to  constant  weight  at  100°C.,  cool, 
wrap  loosely  in  smooth  paper,  crush  into  rather  small  fragments  between  the  fin- 
gers, transfer  carefully  the  crushed  mass,  exclusive  of  the  paper,  to  an  extraction 
tube  or  a  fat  extraction  cartridge.  A  thin  lead  disk  (bottle  cap)  may  be  substituted 
for  the  Schalchen.  The  disk  may  then  be  cut  into  small  pieces  and  placed  in  the 
extraction  tube.  Extract  with  anhydrous  ether  or  petroleum  ether  (b.  p.  45°-60''C. 
and  without  weighable  residue)  in  a  continuous  extraction  apparatus  for  at  least  25 
hours.  In  most  cases  it  is  advisable  to  remove  the  substance  from  the  extractor 
after  the  first  12  hours,  grind  with  sand  to  a  fine  powder,  and  re-extract  for  the  re- 
maining 13  hours.  Transfer  the  extract  to  a  tared  flask,  evaporate  the  solvent,  dry 
to  constant  weight  in  an  oven  at  lOO'C. 

29  Roese-Gottlieb  Method. — Tentative. 

Substances  such  as  butter-scotch,  invariably  yield  extremely  inaccurate  results 
by  the  above  method.  In  such  cases  introduce  4  grams  of  the  material,  or  an  amount 
of  a  uniform  solution  equivalent  to  this  amount  of  the  dry  substance,  into  a  Rohrig 
tube  or  similar  apparatus,  make  up  to  a  volume  of  10  cc.  with  water,  add  1.25  cc. 
of  concentrated  ammonium  hydroxid  and  mix  thoroughly.  Add  10  cc.  of  95%  alco- 
hol and  mix.  Then  add  25  cc.  of  washed  ether  and  shake  vigorously  for  half  a  min- 
ute; then  add  25  cc.  of  petroleum  ether  (b.  p.  below  60°C.),  and  shake  again  for 
half  a  minute.     Allow  to  stand  for  20  minutes  or  until  the  separation  between  the 


132  METHODS    OF   ANALYSIS  [Chap. 

liquids  is  complete.  Draw  off  as  much  as  possible  of  the  ether-fat  solution  (usually 
0.5-0.8  cc.  will  be  left)  into  a  weighed  flask  through  a  small,  rapid  filter.  The  flask 
should  be  weighed  with  a  similar  one  as  a  counterpoise.  Again  extract  the  liquid 
remaining  in  the  tube,  this  time  with  15  cc.  each  of  ether  and  petroleum  ether,  shake 
vigorously  half  a  minute  with  each,  and  allow  to  settle.  Proceed  as  above,  wash- 
ing the  tip  of  the  spigot  and  the  filter  with  a  few  cc.  of  a  mixture  of  equal  parts  of 
the  2  ethers  (previously  mixed  and  free  from  deposited  water).  For  absolutely 
exact  results  the  extraction  must  be  repeated.  This  third  extraction  usually  yields 
not  more  than  about  1  mg.  of  fat,  if  the  previous  ether-fat  solutions  have  been 
drawn  off  closely,  or  an  amount  averaging  about  0.02%  on  a  4  gram  charge.  Evapo- 
rate the  ether  slowly  on  a  steam  bath,  then  dry  the  fat  in  a  boiling  water  oven  until 
the  loss  in  weight  ceases.  Test  the  purity  of  the  fat  by  dissolving  in  a  little  petro- 
leum ether.  Should  a  residue  remain,  wash  the  fat  out  completely  with  petroleum 
ether,  dry  the  residue,  weigh,  and  deduct  the  weight. 

30  PARAFFIN  IN  CONFECTIONERY.-TENTATIVE. 

Add  to  the  ether  extract  in  the  flask,  as  above  obtained,  10  cc.  of  95%  alcohol 
and  2  cc.  of  sodium  hydroxid  solution  (1  to  1),  connect  the  flask  with  a  reflux  con- 
denser, and  heat  for  an  hour  on  the  water  bath,  or  until  saponification  is  complete. 
Remove  the  condenser  and  allow  the  flask  to  remain  on  the  bath  until  the  alcohol 
is  evaporated  and  the  residue  is  dry.  Dissolve  the  residue  as  completely  as  pos- 
sible in  about  40  cc.  of  water  and  heat  on  the  bath,  shaking  frequently.  Wash  into 
a  separatory  funnel,  cool,  and  extract  with  4  successive  portions  of  petroleum  ether, 
which  are  collected  in  a  tared  flask  or  capsule.  Evaporate  the  petroleum  ether 
and  dry  in  the  oven  to  constant  weight. 

Any  phytosterol  or  cholesterol  present  in  the  fat  would  be  extracted  with  the 
paraffin.  The  amount  is  so  insignificant  that  it  may  be  disregarded  generally. 
The  character  of  the  final  residue  should,  however,  be  confirmed  by  determining 
its  melting  point,  specific  gravity,  and  refractive  index. 

31  ALCOHOL  IN  SmUPS  USED  IN    CONFECTIONERY  ("BRANDY   DROPS").— TENTATIVE. 

Collect  in  a  beaker  the  sirup  from  a  sufficient  number  of  pieces  to  yield  30-50 
grams  of  sirup.  Strain  the  sirup  into  a  tared  beaker  and  weigh.  Introduce  the 
sirup  into  a  250-300  cc.  distilling  flask,  dilute  with  half  its  volume  of  water,  attach 
the  flask  to  a  vertical  condenser  and  distil  almost  50  cc,  or  as  much  of  the  liquid  as 
possible  without  causing  charring.  Foaming  may  be  prevented  by  adding  a  little 
tannin,  or  a  piece  of  paraffin  about  the  size  of  a  pea,  to  the  contents  of  the  distil- 
lation flask.  Cool  the  distillate,  make  up  to  volume  with  water,  mix  well,  and 
ascertain  the  specific  gravity  of  the  liquid  by  means  of  a  pycnometer,  and  obtain 
the  corresponding  weight  of  alcohol  in  the  50  cc.  of  distillate  from  XVI,  5.  Cal- 
culate the  per  cent  by  weight  of  alcohol  in  the  candy  filling. 

32  COLORING  MATTER.— TENTATIVE, 
Proceed  as  directed  under  XI. 

33  METALS.— TENTATIVE. 
Proceed  as  directed  under  XII. 


IX]  SACCHARINE  PRODUCTS  133 

HONEY." 

34  PREPARATION  OF  SAMPLE.— TENTATIVE. 

(a)  Liquid  or  strained  honey. — If  the  sample  is  free  from  granulation,  mix  thor- 
oughly by  stirring  or  shaking  before  drawing  weighed  portions  for  the  analytical 
determination.  If  the  honey  is  granulated,  place  the  container,  having  the  stopper 
loose,  in  a  water  bath,  and  heat  at  a  temperature  not  exceeding  50°C.  until  the  sugar 
crystals  dissolve;  mix  thoroughly,  cool,  and  weigh  portions  for  the  analytical  de- 
terminations. If  sediment  such  as  particles  of  comb,  wax,  sticks,  bees,  etc.,  are 
present,  heat  the  sample  to  40°C.  in  a  water  bath  and  filter  through  cheese-cloth 
before  weighing  portions  for  analj'sis. 

(b)  Comb  honey.— Cut  across  the  top  of  the  comb,  if  sealed,  and  separate  com- 
pletely from  the  comb  by  straining  through  a  40  mesh  sieve.  When  portions  of  the 
comb  or  wax  pass  through  the  sieve,  heat  the  sample  as  in  (a)  and  strain  through 
cloth.  If  the  honey  is  granulated  in  the  comb,  heat  until  the  wax  is  liquified,  stir, 
cool,  remove  the  wax  and  take  the  clear  liquid  for  analysis. 

35  MOISTURE. 

Weigh  2  grams  of  the  sample  into  a  tared,  flat-bottomed  aluminium  dish,  having  a 
diameter  of  about  60  mm.  and  containing  10-15  grams  of  fine  quartz  sand,  which  has 
been  previously  washed,  dried  and  ignited,  and  a  small  glass  stirring  rod;  add  5-10 
cc.  of  water  and  thoroughly  incorporate  with  the  sand  and  honey  mixture  by  means 
of  the  rod;  dry  the  dish  and  its  contents  to  constant  weight  in  a  vacuum  oven  at 
a  temperature  not  exceeding  70°C. 

36  ASH.— OFFICIAL. 

Weigh  5-10  grams  of  honey  into  a  platinum  dish,  add  a  few  drops  of  pure  olive 
oil  to  prevent  spattering,  and  heat  carefully  until  swelling  ceases  and  then  ignite 
at  a  temperature  not  above  dull  redness  until  a  white  ash  is  obtained. 

37  SOLUBLE  ASH.— TENTATIVE. 

Proceed  as  directed  under  17. 

38  ALKALINITY  OF  THE  SOLUBLE  ASH.-TENTATIVE. 

Proceed  as  directed  under  18. 

POLARIZATION. 

39  Direct  Polarization. — Tentative. 

(a)  Immediate  direct  polarization. — Transfer  26  grams  of  the  honey  to  a  100 
cc.  flask  with  water,  add  5  cc.  of  alumina  cream,  dilute  to  the  mark  with  water  at 
20°C.,  filter,  and  polarize  immediately  in  a  200  mm.  tube. 

(b)  Constant  direct  polarization. — Pour  the  solution  from  the  tube  used  in  read- 
ing (a)  back  into  the  flask,  stopper,  and  allow  to  stand  for  24  hours.  At  the  end  of 
this  time  again  polarize  the  solution  at  20°C.  in  a  200  mm.  tube. 

(C)  Birotation. — The  difference  between  (a)  and  (b)  gives  the  birotation. 
(d)  Direct  polarization  at  87°C. — Polarize  the  solution,  obtained  in  (b),  at  87°C. 
in  a  jacketed  200  mm.  tube. 


134  METHODS    OF   ANALYSIS  [Chap. 

40  Invert  Polarization. — Tentative. 

(a)  At  SO°C. — Invert  50  cc.  of  the  solution  obtained  in  39  as  directed  under 
VIII,  14  or  16,  and  polarize  at  20°C.  in  a  200  mm.  tube. 

(b)  At  87°C.— Polarize  the  solution,  obtained  as  directed  in  (a),  at  87°C.  in  a  200 
mm.  jacketed  tube. 

41  REDUCING  SUGARS.-TENTATIVE. 

Dilute  10  cc.  of  the  solution,  used  for  direct  polarization,  39,  to  250  cc.  and  de- 
termine reducing  sugars  in  25  cc.  of  this  solution  by  one  of  the  methods  given  under 
VIII,  25,  36,  39  or  56,  respectively.  Calculate  the  result  to  per  cent  of  invert 
sugar. 

42  SUCROSE.— TENTATIVE. 

Proceed  as  directed  under  VIII,  18.  Determine  reducing  sugars  after  inver- 
sion by  diluting  10  cc.  of  the  solution  obtained  in  40,  with  a  small  amount  of  water, 
neutralizing  with  sodium  carbonate,  and  making  up  to  250  cc.  with  water.  Employ 
50  cc.  of  this  solution  for  the  determination,  using  the  same  method  as  in  41 . 

43  LEVULOSE.-TENTATIVE. 

Multiply  the  direct  reading  at  87°C.,  39  (d),  by  1.0315  and  subtract  the  product 
from  the  constant  direct  polarization  at  20°C.,  39  (b):  divide  the  difference  by  2.3919 
to  obtain  the  grams  of  levulose  in  a  normal  weight  of  the  honey.  From  this  figure 
calculate  the  per  cent  of  levulose  in  the  original  sample. 

44  DEXTROSE.— TENTATIVE. 

Subtract  the  per  cent  of  levulose,  obtained  in  43,  from  the  per  cent  of  invert 
sugar,  found  in  41 ,  to  obtain  the  approximate  per  cent  of  dextrose. 

The  dextrose  can  be  determined  more  accurately  by  multiplying  the  per  cent 
of  levulose,  as  found  in  43,  by  the  factor  0.915,  which  gives  its  dextrose  equivalent 
in  copper  reducing  power.  Subtract  this  figure  from  that  of  the  reducing  sugars,  41 , 
calculated  as  dextrose,  to  obtain  the  percentage  of  dextrose  in  the  sample.  (Owing 
to  the  difference  in  the  reducing  powers  of  different  sugars,  the  sum  of  the  dex- 
trose thus  found  and  the  levulose  as  obtained  in  43  will  be  greater  than  the  amount 
of  invert  sugar  obtained  in  41). 

45  DEXTRIN  (APPROXIMATE).-TENTATIVE. 

Transfer  8  grams  of  the  sample  (4  grams  in  the  case  of  dark  colored  honey-dew 
honey)  to  a  100  cc.  flask  (using  not  more  than  4  cc.  of  water)  by  allowing  the  sam- 
ple to  drain  from  the  weighing  dish  into  the  flask  and  then  dissolving  the  residue  in 
2  cc.  of  water.  After  adding  this  solution  to  the  contents  of  the  flask,  rinse  the 
weighing  dish  with  two  1  cc.  portions  of  water  to  which  a  little  alcohol  is  added  sub- 
sequently. Fill  the  flask  to  the  mark  with  absolute  alcohol,  shaking  constantly. 
Set  the  flask  aside  until  the  dextrin  has  collected  on  the  sides  and  bottom  and  the 
liquid  is  clear.  Decant  the  clear  liquid  through  a  filter  paper  and  wash  the  resi- 
due in  the  flask  with  10  cc.  of  95%  alcohol,  pouring  the  washings  through  the  same 
filter.  Dissolve  the  dextrin  in  the  fiask  with  boiling  water  and  filter  through  the 
filter  paper  already  used,  receiving  the  filtrate  in  a  tared  dish,  prepared  as  directed 
under  4.  Rinse  the  flask  and  wash  the  filter  a  number  of  times  with  small  portions 
of  hot  water,  evaporate  on  a  water  bath  and  dry  to  constant  weight  in  vacuo 
at  70°C. 


IXJ  SACCHARINE    PRODUCTS  135 

After  determining  the  weight  of  the  alcohol  precipitate,  dissolve  the  latter  in 
water  and  make  up  to  definite  volume,  using  50  cc.  of  water  for  each  0.5  gram  of  pre- 
cipitate or  part  thereof. 

Determine  reducing  sugars  in  the  solution  both  before  and  after  inversion  as 
directed  under  VIII,  18,  expressing  the  results  as  invert  sugar.  Calculate  sucrose 
from  the  results  thus  obtained  and  subtract  the  sum  of  the  reducing  sugars  before 
inversion  and  sucrose  from  the  weight  of  the  total  alcoholic  precipitate  to  obtain 
the  weight  of  the  dextrin. 

46  FREE  ACID.-TENTATIVE. 

Dissolve  10  grams  of  the  honey  in  water  and  titrate  with  N/10  sodium  hydroxid 
using  phenolphthalein  as  an  indicator.  Express  the  results  in  terms  of  cc.of  N/10 
sodium  hydroxid  required  to  neutralize  100  grams  of  the  sample. 

47  GLUCOSE.-TENTATIVE. 

Qualitative  test. — Dilute  the  honey  with  water  in  the  proportion  of  1  to  1,  then  add 
a  tew  cc.  of  iodin  solution  (1  gram  of  iodin,  3  grams  of  potassium  iodid,  50  cc.  of 
water).  In  the  presence  of  glucose  the  solution  turns  red  or  violet,  the  depth  and 
character  of  the  color  depending  upon  the  quality  and  nature  of  the  glucose  em- 
ployed. A  blank  test  with  a  pure  honey  of  about  the  same  color  should  be  made 
in  order  to  secure  an  accurate  color  comparison.  Should  the  honey  be  dark  and 
the  percentage  of  glucose  very  small,  precipitate  the  dextrin  which  may  be  pres- 
ent by  adding  several  volumes  of  95%  alcohol.  Allow  to  stand  until  the  precipitate 
settles  (do  not  filter),  decant  the  liquid,  dissolve  the  residue  of  dextrins  in  hot 
water,  cool  and  apply  the  above  test  to  this  solution.  A  negative  result  is  not 
proof  of  the  absence  of  glucose  as  some  glucose,  especially  of  high  conversion,  does 
not  give  any  reaction  with  iodin.  ^ 

Quantitative  test. — An  approximate  determination  can  be  made  by  Browne's 
formula  as  follows:  Multiply  the  difference  in  the  polarizations  of  the  invert  solu- 
tion at  20°C.  and  87°C.  by  77  and  divide  this  product  by  the  percentage  of  invert 
sugar  after  inversion  found  in  the  sample.  Multiply  the  quotient  by  100  and  di- 
vide the  product  by  26.7,  to  obtain  the  percentage  of  honey  in  the  sample;  100  per 
cent  minus  the  per  cent  of  honey  gives  the  percentage  of  glucose. 

COMMERCIAL  INVERT  SUGAR.io 

QUALITATIVE  TESTS. 
Fiehe  Test  {Bryan  Modification"). — Tentative. 

48  REAGENT. 

Resorcin  solution. — Dissolve  1  gram  of  resorcin  in  100  cc.  of  hydrochloric  acid, 
sp.  gr.  1.19. 

49  MANIPULATION. 

Introduce  10  cc.  of  a  50%  honey  solution  into  a  test  tube  and  add  5  cc.  of  ether. 
Shake  gently  and  allow  to  stand  for  some  time  until  the  ether  layer  is  clear.  Trans- 
fer 2  cc.  of  this  clear  ether  solution  to  a  small  test  tube  and  add  a  large  drop  of  the 
resorcin  solution.  Shake  and  note  the  color  immediately.  In  the  presence  of  arti- 
ficial invert  sugar,  the  resorcin  assumes  immediately  an  orange-red  color  turning 
to  dark  red. 


136  METHODS    OF   ANALYSIS  [Chap. 

Feder  Anilin  Chlorid  Test.^"^ — Tentative. 

50  REAGENT. 

Anilin  chlorid  solution. — To  100  cc.  of  C.  P.  anilin  add  30  cc.  of  25%  hydrochloric 
acid. 

51  MANIPULATION. 

Introduce  5  grams  of  the  honey  into  a  porcelain  dish  and  add  2.5  cc.  of  the  anilin 
reagent.     A  bright  red  color  indicates  the  presence  of  commercial  invert  sugar. 

52  DIASTASE." 

Mix  1  part  of  honey  with  2  parts  of  sterile  water.  Treat  10  cc.  of  this  solution 
with  1  cc.  of  1%  soluble  starch  solution  and  digest  at  45°C.  for  an  hour.  At  the  end 
of  this  time  test  the  mixture  with  1  cc.  of  iodin  solution  (1  gram  of  iodin,  2  grams 
of  potassium  iodid,  300  cc.  of  water).  Treat  another  10  cc.  portion  of  the  honey 
solution,  mixed  with  1  cc.  of  the  soluble  starch  solution,  without  heating  to  45°C., 
with  the  reagent  and  compare  the  colors  produced.  If  the  original  honey  had  not 
been  heated  sufficiently  to  kill  the  diastase,  an  olive-green  or  brown  coloration  will 
be  produced  in  the  mixture  that  has  been  heated  at  45°C.  Heated  or  artificial 
honey  becomes  blue. 

MAPLE  PRODUCTS. 

53  PREPARATION  OF  SAMPLE.— TENTATIVE. 

(a)  Maple  sirup. — Determine  the  moisture  by  the  method  given  under  54  (a).  If 
the  moisture  is  less  than  35%,  and  there  is  some  mineral  sediment,  pour  the  clear 
sirup  into  a  beaker,  washing  the  sediment  also  into  the  beaker  with  water.  Then 
concentrate  the  sirup  by  boiling  to  a  moisture  content  of  about  35%  (b.  p.  104°C.). 
Set  aside  until  cool,  or  preferably  let  the  covered  material  stand  overnight,  and 
pour  off  the  clear  liquid  for  the  analytical  work.  Where  no  sediment  is  present 
the  sample  is  ready  for  analysis  after  careful  mixing.  Where  sugar  has  crystal- 
lized out,  warm  to  dissolve  the  sugar  before  starting  the  analysis.  It  is  desira- 
ble in  order  to  compare  results  upon  different  samples,  to  reduce  all  results  other 
than  moisture  to  a  dry  substance  basis  as  determined  in  the  clear  sirup. 

(b)  Maple  sugar,  maple  cream,  maple  wax,  etc. — Determine  moisture,  by  the  meth- 
od given  under  54  (b),  in  the  sample  in  its  original  condition  by  thoroughly  mixing, 
if  semi-plastic,  or  by  rubbing  up  in  a  mortar  representative  portions  of  the  product 
if  solid.  For  all  other  analytical  determinations  use  a  solution  prepared  as  fol- 
lows: Weigh  roughly  100  grams  of  the  product  into  a  beaker  and  dissolve  by  boil- 
ing with  200  cc.  of  water.  Decant  the  resulting  sirup  while  hot  through  a  muslin 
filter,  concentrate  by  boiling  to  a  moisture  content  of  35%  (b.  p.  104°C.),  cool,  or 
preferably  let  the  covered  material  stand  overnight,  set  aside  until  clear,  and  use 
this  clear  sirup  for  analysis.  It  is  desirable,  in  order  to  compare  results  upon 
different  samples,  that  all  results  except  moisture  be  expressed  upon  a  dry  basis. 

54  MOISTURE.— TENTATIVE. 

(a)  Maple  sirup. — Proceed  as  directed  under  35  or  10. 

(b)  Maple  sugar,  maple  cream,  etc. — Proceed  as  directed  under  35. 

55  POLARIZATION.-TENTATIVE. 

(a)  Direct  at  20°C. — Proceed  as  directed  under  VIII,  14. 

(b)  Invert  at  ;20°C.— Proceed  as  directed  under  VIII,  14. 

(C)   Invert  at  87°C. — Proceed  as  directed  under  25  to  detect  commercial  glucose. 


IX]  SACCHARINE    PRODUCTS  137 

53  REDUCING  SUGARS  AS  INVERT  SUGAR.-TENTATIVE. 

(a)  Before  inversion. — Proceed  as  directed  under  VIII,  25,  using  an  aliquot  of 
the  solution  used  for  direct  polarization,  55  (a),  and  only  neutral  lead  acetate  for 
clarification. 

(b)  After  inversion. — Proceed  as  directed  under  VIII,  25,  using  an  aliquot  of 
the  solution  used  for  the  invert  polarization,  55  (b),  and  only  neutral  lead  acetate 
for  clarification. 

SUCROSE. 

57  Bij  Polarization. — Tentative. 
Proceed  as  directed  under  VIII,  14  or  16. 

58  By  Reducing  Sugars  Before  and  After  Inversion. — Tentative. 
Proceed  as  directed  under  VIII,  18. 

59  TOTAL  ASH.— TENTATIVE. 
Proceed  as  directed  under  13. 

80  SOLUBLE  AND  INSOLUBLE  ASH.— TENTATIVE. 

Proceed  as  directed  under  17. 

61  ALKALINITY  OF  THE  SOLUBLE  ASH.— TENTATIVE. 

Proceed  as  directed  under  18. 

62  ALKALINITY  OF  THE  INSOLUBLE  ASH.— TENTATIVE. 

Proceed  as  directed  under  19. 

LEAD  NUMBER  (WINTON).— TENTATIVE. 

63  REAGENTS. 

Standard  basic  lead  acetate  solution. — Boil  430  grams  of  normal  lead  acetate  and 
130  grams  of  litharge,  for  30  minutes,  or  boil  560  grams  of  Home's  dry  basic  lead 
acetate  with  1  liter  of  water,  cool,  allow  to  settle  and  dilute  the  supernatant  liquid 
to  1.25  sp.  gr.  To  a  measured  amount  of  this  solution  add  4  volumes  of  water  and 
filter  if  not  perfectly  clear.  The  solution  should  be  standardized  each  time  a  set 
of  determinations  is  made. 

If  the  directions  for  preparing  the  basic  lead  acetate  are  not  carried  out  care- 
fully, the  use  of  Home's  dry  basic  lead  acetate  is  preferable. 

64  DETERMINATION  OF  LEAD  IN  THE  BLANK. 

Transfer  25  cc.  of  the  standard  basic  lead  acetate  to  a  100  cc.  flask,  add  a  few  drops 
of  acetic  acid,  and  make  up  to  the  mark  with  water.  Shake  and  determine  lead 
sulphate  in  10  cc.  of  the  solution  as  directed  under  65.  The  use  of  the  acid  is  im- 
perative in  this  case  to  keep  the  lead  in  solution,  when  diluted  with  water. 

65  DETERMINATION. 

Transfer  25  grams  of  the  sample  to  a  100  cc.  flask  by  means  of  water.  Add  25 
cc.  of  the  standard  basic  lead  acetate  and  shake,  fill  to  the  mark,  shake,  and  allow  to 
stand  for  at  least  3  hours  before  filtering.  Pipette  10  cc.  of  the  clear  filtrate  into 
a  250  cc.  beaker,  add  40  cc.  of  water  and  1  cc.  of  concentrated  sulphuric  acid,  shake 
and  add  100  cc.  of  95%  alcohol.     Allow  to  stand  overnight,  filter  on  a  tared  Gooch, 


138  METHODS    OF   ANALYSIS  [Chap. 

wash  with  95%  alcohol,  dry  in  a  water  oven,  and  ignite  in  a  muffle  or  over  a  Bun- 
sen  burner,  applying  the  heat  gradually  at  first,  and  avoiding  a  reducing  flame. 
Cool  and  weigh.  Subtract  the  weight  of  lead  sulphate  so  found  from  the  weight  of 
lead  sulphate  found  in  the  blank,  64,  and  multiply  by  the  factor  27.325.  The  use 
of  this  factor  gives  the  lead  number  directly  without  the  various  calculations  other- 
wise required.  * 
MALIC-ACID  VALUE. 

66  Cowles  Melhod.^^ — Tentative. 

Weigh  6.7  grams  of  the  sample  into  a  200  cc.  beaker,  add  5  cc.  of  water,  then  2 
cc.  of  a  10%  calcium  acetate  solution  and  stir.  Add  gradually,  and  with  constant 
stirring,  100  cc.  of  95%  alcohol,  and  agitate  the  solution  until  the  precipitate  set- 
tles, or  let  stand,  until  the  supernatant  liquid  is  clear.  Filter  off  the  precipitate 
and  wash  with  75  cc.  of  85%  alcohol.  Dry  the  filter  paper  and  ignite  in  a  platinum 
dish.  Add  10  cc.  of  N/10  hydrochloric  acid  and  warm  gently  until  all  the  lime 
dissolves.  Cool  and  titrate  back  with  N/10  sodium  hydroxid,  using  methyl  orange 
as  an  indicator.  The  difference  in  cc.  divided  by  10  represents  the  malic  acid  value 
of  the  sample.  Previous  to  use  the  reagents  should  be  tested  by  a  blank  determina- 
tion and  any  necessary  corrections  applied. 

67  METALS.— TENTATIVE. 
Proceed  as  directed  under  XII. 

SUGAR  HOUSE  PRODUCTS. 

SUCROSE  IN  BEETS. 

68  Alcohol  Extraction  Method  {Herzfeld  Modification^^). — Tentative. 

Weigh  26  grams  of  the  beet  pulp  and  transfer  to  a  100  cc.  flask  with  about  50  cc. 
of  90%  alcohol  and  3-5  cc.  of  basic  lead  acetate  solution.  Connect  a  reflux  condenser 
to  the  flask  and  place  on  a  boiling  water  bath  for  10-15  minutes.  Then  pour  the 
whole  into  a  Soxhlet  extractor,  washing  out  the  flask  with  fresh  portions  of  90% 
alcohol.  Connect  the  same  100  cc.  flask  to  the  extractor,  and  fit  the  latter  with 
a  return  condenser.  Add  90%  alcohol  until  the  siphon  is  started  and  the  flask  is 
about  three  fourths  full.  Place  the  flask  in  a  covered  water  bath  kept  at  a  heat 
that  will  allow  the  alcohol  to  boil  freely.  Continue  the  extraction  for  .1-4  hours, 
or  until  a  test  of  the  alcohol  in  the  extractor  gives  no  color  withalpha-naphthol 
solution  when  tested  as  follows:  Introduce  into  a  test  tube  a  few  drops  of  the  alco- 
hol coming  from  the  extractor,  add  4  or  5  drops  of  a  20%  alcoholic  alpha-naphthol 
solution  and  2  cc.  of  water.  Shake  well,  tip  the  tube,  and  allow  2-5  cc.  of  colorless 
concentrated  sulphuric  acid  to  flow  down  the  side  of  the  tube;  then  hold  the  tube 
upright  and,  if  sucrose  is  present,  a  color  varying  from  a  faint  to  a  deep  violet  will 
be  noted  at  the  junction  of  the  two  liquids.  On  shaking,  the  whole  solution  becomes 
a  blue  violet  color.  This  test  is  suitable  for  this  work,  but  it  must  be  remembered 
that  other  substances  besides  sucrose  give  this  color  reaction. 

Remove  the  flask,  transfer  to  a  100  cc.  graduated  flask,  cool  to  the  standard 
temperature,  dilute  to  the  mark  with  90%  alcohol,  shake  and  filter,  keeping  the 
funnel  covered  with  a  watch  glass.     Polarize  in  a  200  mm.  tube. 

Avoid  evaporation  and  changes  of  temperature  and  also  use  a  minimum  amount 
of  basic  acetate  for  clarification,  3  cc.  rather  than  5  cc.  By  digesting  the  beet 
pulp  with  the  alcohol  before  extraction,  the  time  of  extraction  is  gieUly  shortened 
the  pulp  becomes  thoroughly  impregnated  with  the  alcohol,  and  all  the  air  is  re- 
moved, resulting  in  a  good  extraction  of  the  whole  material.     If  the  pulp  is  fine 


IX]  SACCHARINE    PRODUCTS  139 

and  tends  to  clog  the  siphon,  alcohol-washed  cotton  may  be  used  as  a  plug  in  the 
extractor  before  adding  the  beet  pulp,  and  a  fine  mesh  screen  may  be  placed  over 
the  pulp  to  keep  the  whole  compact  in  the  extractor. 

69  Pellet  Aqueous  Method^*  (Hot  Digestion). — Tentative. 

Weigh  52  grams  of  the  beet  cuttings  and  transfer  them  with  water  to  a  wide- 
mouthed  flask  graduated  to  a  content  of  201.2  cc;  add  5-10  cc.  of  basic  lead  acetate 
solution,  fill  the  flask  to  the  mark  with  hot  water,  and  shake.  Immerse  the  flask 
in  a  water  bath  at  80°C.  and  rotate  at  intervals.  Add  water  from  time  to  time  so 
that  at  the  end  of  the  heating  (about  30  minutes)  the  water  in  the  flask  is  a  little 
above  the  mark.  Remove  the  flask  from  the  water  bath  and  allow  it  to  cool  to 
standard  temperature.  Add  sufficient  concentrated  acetic  acid  to  make  the  solu- 
tion very  slightly  acid  (generally  less  than  0.5  cc.)  and  a  few  drops  of  ether  to  break 
the  foam.  Make  up  to  the  mark,  mix  thoroughly,  filter,  and  polarize  in  a  200  mm. 
tube. 

The  fineness  of  the  pulp  governs  the  time  of  heating.  Add  enough  water  at  the 
start  and  maintain  this  volume  during  the  extraction,  so  that  not  more  than  5  cc.  of 
water  will  be  necessary  to  complete  the  volume  after  cooling.  The  proportion  of 
pulp  to  water  must  not  be  increased  beyond  the  prescribed  amount,  for  when  smaller 
proportionsof  water  to  pulp  are  used  and  then  a  large  quantity  of  water  is  added  at 
the  last  to  make  up  to  volume,  the  sugar  does  not  become  equally  diffused  and  the 
results  are  too  low.  Differences  of  over  1%  in  sugar  content  may  be  caused  by  lack 
of  care  in  this  particular. 

70  Hot  Water  Digestion  Method. — Tentative. 
(Herzfeld  Modification  of  the  Sachs  Le  Docte  Method'^) 

There  are  needed  nickel-plated  sheet  iron  vessels,  11  cm.  high,  6  cm.  body  diame- 
ter, and  4  cm.  mouth  diameter,  also  stoppers  covered  with  tin  foil  to  fit  the  same. 

Weigh  26  grams  of  the  beet  pulp  on  a  watch  glass  (small  enough  to  go  into  the 
neck  of  the  beaker)  and  transfer  to  the  metal  beaker,  add  177  cc.  of  dilute  basic 
lead  acetate  solution  (5  parts  of  basic  lead  acetate  solution  (sp.  gr.  1.25)  to  100 
parts  of  water),  shake  and  stopper  lightly.  Submerge  the  beaker  in  a  water  bath 
at  75°-80°C.  for  30  minutes,  shaking  intermittently.  When  all  the  air  has  been 
expelled  (generally  after  5  minutes),  tighten  the  stopper.  After  30  minutes,  shake, 
cool  to  standard  temperature,  filter,  add  a  drop  of  acetic  acid  to  the  filtrate  and 
polarize  in  a  400  mm.  tube.     The  reading  is  the  per  cent  of  sugar  in  the  beet  pulp. 

BIBLIOGRAPHY. 

1  Browne.     Handbook  of  Sugar  Analysis.     1912,  p.  16. 

'  Wiss.  Abh.  der  Kaiserlichen  Normal-Eichungs-Kommission,  1900,  2:  153;  U.  S. 
Bur.  Standards,  Circ.  19,  5th  ed.,  p.  26. 

»  Intern.  Sugar  J.,  10:  69;  U.  S.  Bur.  Chem.  Bull.  122,  p.  169. 

*  Z.  anal.  Chem.,  1899,  38:  345. 

*  Leach.     Food  Inspection  and  Analysis.     1913,  p.  624. 
«  Analyst,  1890,  21:  182. 

^  Leach.     P'ood  Inspection  and  Analysis.     1913,  p.  622. 

8  U.  S.  Bur.  Chem.  Bulls.  110  and  154;  Z.  Nahr.  Genussm.,  1909,  18:  625. 

9  U.  S.  Bur.  Chem.  Bull.  110,  p.  60. 
loibid.,  110  and  154. 

"  Ibid.,  154,  p.  15. 

12  Analyst,  1911,  36:586. 

"  Z.  Nahr.  Genussm.,  1910,  19:  72. 

>*  J.  Am.  Chem.  Soc,  190S.  30:  1285. 

"  U.  S.  Bur.  Chem.  Bull.  146,  p.  17. 

'6  Ibid.,  p.  18. 

1'  Ibid.,  p.  19. 


X.  FOOD  PRESERVATIVES.— TENTATIVE. 

SALICYLIC  ACID. 

1  PREPARATION  OF  SAMPLE. 

(a)  Non-alcoholic  liquids. — Many  liquids  may  be  extracted  directly  as  described 
in  2  or  4  without  further  treatment.  If  gums  or  mucilaginous  substances  are  present, 
pipette  100  cc.  into  a  250  cc.  volumetric  flask,  add  about  5  grams  of  sodium  chlorid, 
shake  until  the  latter  is  dissolved,  make  up  to  the  mark  with  alcohol,  shake  vigor- 
ously, allow  the  mixture  to  stand  for  10  minutes  with  occasional  shaking,  filter 
through  a  dry  folded  filter  and  treat  an  aliquot  of  the  filtrate  as  directed  under  (b). 

(b)  Alcoholic  liquids. — Make  200  cc.  of  the  sample  alkaline  with  sodium  hydroxid 
solution,  using  litmus  as  an  indicator,  and  evaporate  on  a  steam  bath  to  about  one 
third  its  original  volume.  Dilute  to  the  original  volume  with  water  and  filter,  if 
necessary,  through  a  dry  filter. 

(C)  Solid  or  semi-solid  substances. — Grind  the  sample  and  mix  thoroughly.  Trans- 
fer a  convenient  quantity  (50-200  grams  according  to  the  consistency  of  the  sam- 
ple) to  a  500  cc.  volumetric  flask,  add  sufficient  water  to  make  a  volume  of  about 
400  cc,  shake  until  the  mixture  becomes  uniform,  add  2-5  grams  of  calcium  chlorid, 
shake  until  the  latter  is  dissolved,  render  distinctly  alkaline  with  sodium  hydroxid 
solution,  using  litmus  as  an  indicator,  fill  to  the  mark  with  water,  shake  thoroughly, 
allow  to  stand  for  at  least  2  hours  shaking  frequently  and  filter  through  a  large 
folded  filter. 

DETECTION  AND  ESTIMATION. 

2  Ferric  Chlorid  Test. — Qualitative. 

Introduce  50  cc.  of  the  sample  or  an  equivalent  amount  of  an  aqueous  extract, 
prepared  as  directed  under  1 ,  into  a  separatory  funnel,  add  one  tenth  its  volume 
of  dilute  hydrochloric  acid  (1  to  3)  and  extract  with  50  cc.  of  ether.  If  the  mixture 
emulsifies,  add  10-15  cc.  of  petroleum  ether  (b.  p.  below  60°C.)  and  shake.  If  this 
treatment  fails  to  break  the  emulsion  whirl  the  mixture  in  a  centrifuge,  or  allow  it 
to  stand  until  a  considerable  portion  of  the  aqueous  layer  has  separated,  run  off 
the  latter,  shake  vigorously  and  again  allow  to  separate.  Wash  the  ether  layer 
with  two  5  cc.  portions  of  water,  evaporate  the  greater  portion  of  the  ether  in  a  por- 
celain dish  on  a  steam  bath,  allow  the  remainder  to  evaporate  spontaneously  and 
add  a  drop  of  0.5%  ferric  chlorid  solution.     A  violet  color  indicates  salicylic  acid. 

If  coloring  matter  or  other  interfering  substances  are  present  in  the  residue 
left  after  evaporation  of  the  ether,  purify  the  salicylic  acid  by  one  of  the  following 
methods: 

(a)  Dissolve  the  residue  from  the  ether  extract,  obtained  as  directed  above, 
in  about  25  cc.  of  ether,  transfer  the  latter  to  a  separatory  funnel  and  shake  with 
an  equal  quantity  of  water,  made  distinctly  alkaline  with  several  drops  of  am- 
monium hydroxid.  Allow  to  separate,  filter  the  aqueous  laj'er  through  a  wet  fil- 
ter into  a  porcelain  dish,  evaporate  almost  to  dryness,  and  test  the  residue  as  directed 
above. 

(b)  Drj'  the  residue  from  the  ether  extract,  obtained  as  directed  above,  in  a 
desiccator  over  sulphuric  acid  and  extract  with  several  10  cc.  portions  of  carbon 

141 


142  METHODS   OF  ANALYSIS  [Chap. 

disulphid  or  petroleum  ether  (b.  p.  below  60°C.),  rubbing  the  contents  of  the  dish 
with  a  glass  rod,  and  filtering  the  successive  portions  of  the  solvent  through  a  dry 
paper  into  a  second  porcelain  dish.  Evaporate  the  greater  portion  of  the  solvent 
on  a  steam  bath,  allow  the  remainder  to  evaporate  spontaneously  and  test  the 
residue  as  directed  above. 

(C)  Transfer  the  residue  from  the  ether  extract,  obtained  as  directed  above, 
to  a  small  porcelain  crucible  by  means  of  a  few  cc.  of  ether  and  allow  the  solvent 
to  evaporate  spontaneously.  Cut  a  hole  in  a  piece  of  asbestos  board  sufficiently 
large  to  admit  about  two  thirds  of  the  crucible,  cover  the  latter  with  a  small,  round- 
bottomed  flask  filled  with  cold  water,  and  heat  over  a  small  Bunsen  flame  until 
any  salicylic  acid  present  has  sublimed  and  condensed  upon  the  bottom  of  the 
flask.    Test  the  sublimate  as  directed  above. 

3  Jorissen's  Test.^ — Qualitative. 

Dissolve  the  residue  from  the  ether  extract,  obtained  as  directed  under  2,  or, 
in  case  impurities  are  present,  the  purified  material  obtained  as  directed  under  2 
(a),  (b)  or  (C)  in  a  little  hot  water.     Cool  10  cc.  of  the  solution  in  a  test  tube,  add 

4  or  5  drops  of  10%  potassium  nitrite  solution,  4  or  5  drops  of  50%  acetic  acid  and 
1  drop  of  10%  cupric  sulphate  solution,  mix  thoroughly  and  heat  to  boiling.  Boil 
for  half  a  minute  and  allow  to  stand  for  1-2  minutes.  In  the  presence  of  salicylic 
acid  a  blood  red  color  will  develop. 

Colorimetric  Method. — Quantitative. 

4  EXTRACTION. 

Pipette  a  convenient  portion  of  the  sample  (100  cc.  or  a  volume  representing  not 
less  than  20  grams  of  the  original  sample)  or  a  solution,  prepared  as  in  1 ,  into  a  sepa- 
ratory  funnel,  make  the  solution  neutral  to  litmus  with  dilute  hydrochloric  acid 
(1  to  3)  and  add  an  excess  of  concentrated  hydrochloric  acid  equivalent  to  2  cc. 
of  acid  for  each  100  cc.  of  solution.  Extract  with  4  separate  portions  of  ether, 
using  for  each  extraction  a  volume  of  ether  equivalent  to  half  the  volume  of  the 
aqueous  layer.  If  an  emulsion  forms  on  shaking,  this  may  usually  be  broken  by 
adding  a  little  (one  fifth  the  volume  of  the  ether  layer)  petroleum  ether  (b.  p.  be- 
low 60°C.)  and  shaking  again  or  by  centrifugalizing.  If  an  emulsion  still  persists, 
allow  it  to  remain  with  the  aqueous  layer.  If  an  emulsion  remains  after  the 
fourth  extraction,  separate  it  from  the  clear  ether  and  the  clear  aqueous  layer 
and  extract  it  separately  with  2-3  small  portions  of  ether.  Combine  the  ether 
extracts,  wash  with  one  tenth  their  volume  of  water,  allow  the  layers  to  separate 
and  reject  the  aqueous  layer.  Wash  in  this  way  until  the  aqueous  layer  after  sepa- 
ration yields  a  yellow  color  upon  the  addition  of  methyl  orange  and  2  drops  of  N/10 
sodium  hydroxid.  Distil  slowly  the  greater  part  of  the  ether,  transfer  the  remainder 
to  a  jjorcelain  dish  and  allow  the  ether  to  evaporate  spontaneously.  If  there  are 
no  interfering  substances  present,  proceed  as  directed  in  5.  If  such  interfering 
substances  are  present,  purify  the  residue  by  one  of  the  following  methods: 

(a)  Dry  thoroughly  the  residue  in  vacuo  over  sulphuric  acid  and  extract  with 
10  portions  of  10-15  cc.  each  of  carbon  disulphid  or  petroleum  ether  (b.  p.  below 
60°C.),  rub  the  contents  of  the  dish  with  a  glass  rod  and  filter  the  successive  portions 
of  the  solvent  through  a  dry  filter  into  a  porcelain  dish.  Test  the  extracted  resi- 
due with  a  drop  of  ferric  alum  solution  and,  if  it  gives  a  reaction  for  salicylic  acid, 
dissolve  it  in  water  and  reextract  with  ether,  proceeding  as  directed  above.  Dis- 
til the  greater  portion  of  the  carbon  disulphid  or  petroleum  ether  and  allow  the 
remainder  to  evaporate  spontaneously.     Proceed  as  directed  in  5. 


X]  FOOD    PRESERVATIVES  143 

(b)  Dissolve  the  residue  in  40-50  cc.  of  ether.  Transfer  the  ether  solution  to 
a  separatory  funnel  and  extract  with  3  successive  15  cc.  portions  of  1%  ammonium 
hydroxid.  (If  fat  is  known  to  be  present  in  the  original  ether  e.xtract,  extract  the 
latter  directly  with  4  portions  of  the  ammonium  hydroxid  instead  of  3.)  Combine 
the  alkaline  aqueous  extracts,  acidify,  again  extract  with  ether  and  wash  the  com- 
bined ether  extracts  as  directed  above.  Distil  slowly  the  greater  portion  of  the 
ether,  allow  the  remainder  to  evaporate  spontaneously  and  proceed  as  directed  in  5. 

5  DETERMINATION. 

Dissolve  the  residue,  obtained  in  4,  in  a  small  amount  of  hot  water  and,  after 
cooling,  dilute  to  a  definite  volume  (usually  50-100  cc),  dependent  on  the  amount 
of  salicylic  acid  present.  If  the  solution  is  not  clear,  filter  through  a  dry  filter. 
Dilute  aliquots  of  the  solution  and  treat  with  a  few  drops  of  0.5%  ferric  chlorid 
solution  or  2%  ferric  alum  solution. 

The  ferric  alum  solution  should  be  boiled  until  a  precipitate  appears,  allowed  to 
settle,  and  filtered.  The  acidity  of  the  solution  is  slightly  increased  in  this  manner, 
but  it  remains  clear  for  a  considerable  time,  and  the  turbidity  caused  by  its  dilution 
with  water  is  much  less  and  does  not  appear  as  soon  as  when  the  unboiled  solution 
is  used.     This  turbidity  interferes  with  the  exact  matching  of  the  color. 

Compare  the  colors  developed  with  that  obtained  when  a  standard  salicylic  acid 
solution  (containing  1  mg.  of  salicylic  acid  in  50  cc.)  is  similarly  treated,  using 
Nessler  tubes  or  a  colorimeter.  In  either  case,  and  especially  with  ferric  chlorid, 
avoid  an  excess  of  the  reagent,  although  an  excess  of  0.5  cc.  of  2%  ferric  alum  solu- 
tion may  be  added  to  50  cc.  of  the  comparison  solution  of  salicylic  acid  without 
impairing  the  results. 

BENZOIC  ACID. 
PREPARATION  OF  SAMPLE. 

6  General  Method. 

If  solid  or  semi-solid,  grind  the  sample,  and  mix  thoroughly.  Transfer  about 
150  grams  to  a  500  cc.  graduated  flask,  add  enough  pulverized  sodium  chlorid  to 
saturate  the  water  in  the  sample,  render  alkaline  with  sodium  hj^droxid  solution 
or  milk  of  lime,  and  dilute  to  the  mark  with  a  saturated  salt  solution.  Allow  to 
stand  for  at  least  2  hours,  with  frequent  shaking,  and  filter.  If  the  sample  contains 
large  amounts  of  matter  precipitable  by  salt  solution,  it  is  advisable  to  follow  a 
method  similar  to  that  given  under  7  (d).  When  alcohol  is  present,  follow  the 
method  given  under  7  (C).  When  large  amounts  of  fats  are  present,  make  an 
alkaline  extraction  of  the  filtrate  before  proceeding  as  directed  under  1 1 . 

7  Special  Methods. 

(a)  Ketchup. — Saturate  the  water  in  150  grams  of  ketchup  by  adding  15  grams  of 
pulverized  sodium  chlorid.  Transfer  the  mixture  to  a  500  cc.  graduated  flask,  rins- 
ing with  about  150  cc.  of  saturated  sodium  chlorid  solution.  Make  slightly  alkaline 
to  litmus  paper  with  strong  sodium  hydroxid  solution  and  fill  to  the  mark  with  satu- 
rated salt  solution.  Allow  to  stand  for  at  least  1  hours,  shaking  frequently. 
Squeeze  through  a  heavy  muslin  bag  and  then  filter  through  a  large  folded  filter. 

(b)  Jellies,  jams,  preserves  and  marjnalades. — Dissolve  150  grams  of  the  sam- 
ple in  about  300  cc.  of  saturated  salt  solution.  Add  15  grams  of  pulverized  sodium 
chlorid.  Make  alkaline  to  litmus  paper  with  milk  of  lime.  Transfer  to  a  500  cc. 
graduated  flask  and  dilute  to  the  mark  with  saturated  salt  solution.     Allow  to 


144  METHODS    OF   ANALYSIS  [Chap. 

stand  for  at  least  2  hours,  shaking  frequently,  centrifugalize  if  necessary,  and 
filter  through  a  large  folded  filter. 

(C)  Cider  containing  alcohol,  and  similar  products. — Make  250  cc.  of  the  sample 
alkaline  to  litmus  paper  with  sodium  hydroxid  solution  and  evaporate  on  the  steam 
bath  to  about  100  cc.  Transfer  the  sample  to  a  250  cc.  graduated  flask,  add  30  grams 
of  pulverized  sodium  chlorid  and  shake  until  dissolved.  Dilute  to  the  original 
volume,  250  cc,  with  saturated  salt  solution,  allow  to  stand  for  at  least  2  hours, 
shaking  frequently,  and  filter  through  a  folded  filter. 

(d)  Salted  or  dried  fish. — Wash  50  grams  of  the  ground  sample  into  a  500  cc.  gradu- 
ated flask  with  water.  Make  slightly  alkaline  to  litmus  paper  with  strong  sodium 
hydroxid  solution  and  dilute  to  the  mark  with  water.  Allow  to  stand  for  at  least 
2  hours,  shaking  frequently,  and  then  filter  through  a  folded  filter.  Pipette  accu- 
rately as  large  a  portion  of  the  filtrate  as  possible  (at  least  300  cc.)  into  a  second 
500  cc.  flask.  Add  30  grams  of  the  pulverized  sodium  chlorid  for  each  100  cc.  of 
solution.  Shake  until  the  salt  has  dissolved  and  dilute  to  the  mark  with  saturated 
salt  solution.  Mix  thoroughly  and  filter  off  the  precipitated  protein  matter  on 
a  folded  filter. 

8  DETECTION  AND  ESTIMATION. 

Extract  benzoic  acid  as  directed  under  2  or  4.  If  benzoic  acid  is  present  in 
considerable  quantity,  it  will  crystallize  from  the  ether  in  shining  leaflets  having 
a  characteristic  odor  on  heating.  Dissolve  the  residue  in  hot  water,  divide  into 
2  portions,  and  test  according  to  9  or  10. 

9  Ferric  Chlorid  Test. — Qualitative. 

Make  the  solution  from  8  alkaline  with  ammonium  hydroxid,  expel  the  excess  of 
ammonia  by  evaporation,  dissolve  the  residue  in  water,  and  add  a  few  drops  of  a 
neutral  0.5%  ferric  chlorid  solution.  A  brownish  precipitate  of  ferric  benzoate 
indicates  the  presence  of  benzoic  acid. 

10  Modified  Mohler  Test.^ — Qualitative. 

Add  to  the  water  solution,  prepared  as  described  under  8,  1-3  cc.  of  N/3  sodium 
hydroxid  and  evaporate  to  dryness.  To  the  residue,  add  5-10  drops  of  concentrated 
sulphuric  acid  and  a  small  cr3^stal  of  potassium  nitrate.  Heat  for  10  minutes  in 
a  glycerol  bath  at  120°-130°C.,  or  for  20  minutes  in  a  boiling  water  bath.  The 
temperature  must  not  exceed  130°C.  After  cooling  add  1  cc.  of  water  and  make 
distinctly  ammoniacal;  boil  the  solution  to  decompose  any  ammonium  nitrite  which 
may  have  been  formed.  Cool  and  add  a  drop  of  fresh,  colorless  ammonium  sulphid, 
without  allowing  the  layers  to  mix.  A  red-brown  ring  indicates  benzoic  acid. 
On  mixing,  the  color  diffuses  through  the  whole  liquid  and,  on  heating,  finally  changes 
to  greenish  yellow.  This  differentiates  benzoic  acid  from  salicylic  acid  or  cinnamic 
acid.  The  last  two  form  colored  compounds,  which  are  not  destroyed  by  heating. 
The  presence  of  phenolphthalein  interferes  with  this  test. 

11  Quantitative  Method. 

Pipette  a  convenient  portion  (100-200  cc.)  of  the  filtrate,  obtained  in  6  or  7,  into  a 
separatory  funnel.  Neutralize  the  solution  to  litmus  paper  with  hydrochloric 
acid  (1  to  3)  and  add  an  excess  of  5  cc.  of  the  same  acid.  In  the  case  of  salted  fish 
a  precipitation  of  protein  matter  usually  occurs  on  acidifying,  but  the  precipitate 
does  not  interfere  with  the  extraction.  Extract  carefully  with  chloroform,  using 
successive  portions  of  70,  50,  40,  and  30  cc.     To  avoid  an  emulsion,  shake  cautiously 


X]  FOOD    PRESERVATIVES  145 

each  time.  The  chloroform  layer  usually  separates  readily  after  standing  a  few 
minutes.  If  an  emulsion  forms,  break  it:  (1)  by  stirring  the  chloroform  layer  with 
a  glass  rod;  (2)  by  drawing  it  off  into  a  second  fimnel  and  giving  1  or  2  sharp  shakes 
from  one  end  of  the  funnel  to  the  other;  or  (3)  by  centrifugalizing  for  a  few  moments. 
As  this  is  a  progressive  extraction,  draw  off  carefully  as  much  of  the  clear  chloro- 
form solution  as  possible  after  each  extraction,  but  do  not  draw  off  any  of  the  emul- 
sion with  the  chloroform  layer.  If  this  precaution  is  taken,  the  chloroform  extract 
need  not  be  washed. 

Transfer  the  combined  chloroform  extracts  to  a  porcelain  evaporating  dish, 
rinse  the  container  several  times  with  a  few  cc.  of  chloroform,  and  evaporate  to 
dryness  at  room  temperature  in  a  current  of  air  dried  over  calcium  chlorid. 

The  extract  may  also  be  transferred  from  the  separator^  funnel  to  a  300  cc.  Erlen- 
meyer  flask,  rinsing  the  separatory  funnel  3  times  with  5-10  cc.  of  chloroform.  Dis- 
til very  carefully  to  about  one  fourth  the  original  volume,  keeping  the  temperature 
down  so  that  the  chloroform  comes  over  in  drops,  not  in  a  steady  stream.  Then 
transfer  the  residue  to  a  porcelain  evaporating  dish,  rinsing  the  flask  3  times  with 
5-10  cc.  portions  of  chloroform,  and  allow  to  evaporate  to  dryness  spontaneously. 

Dry  the  residue  overnight  (or  until  no  odor  of  acetic  acid  can  be  detected  if  the 
product  is  a  ketchup)  in  a  desiccator  containing  sulphuric  acid.  Dissolve  the  resi- 
due of  benzoic  acid  in  30-50  cc.  of  neutral  alcohol,  add  about  one  fourth  this  volume 
of  water,  1  or  2  drops  of  phenolphthalein,  and  titrate  with  N/20  sodium  hydroxid 
(1  cc.  is  equivalent  to  0.0072  gram  of  anhydrous  sodium  benzoate). 

SACCHARIN. 

12  Qualilative  Test. 

Extract  with  ether  (after  maceration  and  exhaustion  with  water,  if  necessary), 
as  directed  in  1  and  4.  Allow  the  ether  extract  to  evaporate  spontaneously  and 
note  the  taste  of  the  residue.  The  presence  of  saccharin,  to  the  extent  of  20  mg. 
per  liter,  is  indicated  by  a  sweet  taste.  Confirm  by  heating  with  sodium  hydroxid, 
as  described  below,  and  detecting  the  salicylic  acid  formed  thereby.  A  sweet  taste, 
suggesting  the  presence  of  a  trare  of  saccharin,  has  been  obtained  frequently  in 
saccharin-free  wines,  due  to  the  so-called  "false  saccharin". 

Acidify  50  cc.  of  a  liquid  food  or  the  aqueous  extract  of  50  grams  of  a  solid  or  semi- 
solid, prepared  as  directed  in  1  (C),  and  extract  with  ether  as  directed  in  13.  Dis- 
solve the  residue,  remaining  after  evaporation  of  the  ether,  in  a  little  hot  water 
and  test  a  small  portion  of  this  solution  for  salicylic  acid  as  directed  under  2  or  3. 
Dilute  the  remainder  of  the  solution  to  about  10  cc,  and  add  2  cc.  of  sulphuric 
acid  (1  to  3).  Heat  to  boiling  and  add  a  slight  excess  of  5%  potassium  perman- 
ganate solution,  drop  by  drop;  partly  cool  the  solution,  dissolve  a  piece  of  sodium 
hydroxid  in  it,  and  filter  the  mixture  into  a  silver  dish  (silver  crucible  lids  are  well 
adapted  to  the  purpose);  evaporate  to  dryness  and  heat  for  20  minutes  at  210"- 
215°C.  Dissolve  the  residue  in  water,  acidify  with  hydrochloric  acid  and  test  the 
ether  extract  for  salicylic  acid  as  directed  under  2  or  3.  By  this  method  all  the 
so-called  "false  saccharin"  and  the  salicylic  acid  naturally  present  (also  added 
salicylic  acid  when  not  present  in  too  large  an  amount)  are  destroyed,  while  5  mg. 
of  saccharin  per  liter  are  detected  with  certainty. 

13  Quantilalive  Method. 

Pipette  100  cc.  of  the  sample,  or  a  convenient  portion  of  a  solution,  prepared 
as  directed  under  1 ,  representing  not  less  than  20  grams  of  the  sample,  into  a  sepa- 


146  METHODS   OF  ANALYSIS  [Chap. 

ratory  funnel,  make  the  solution  neutral  to  litmus  with  dilute  hydrochloric  acid 
(1  to  3)  and  then  add  concentrated  hydrochloric  acid  in  the  proportion  of  5  cc.  for 
each  100  cc.  of  solution.  Extract  with  4  separate  portions  of  ether  using,  for  each 
extraction,  a  volume  of  ether  equivalent  to  half  the  volume  of  the  aqueous  layer. 
If  the  mixture  emulsifies  on  shaking,  this  difficulty  may  be  overcome  as  directed 
under  4.  Wash  the  combined  ether  extracts  with  two  5  cc.  portions  of  water,  re- 
move the  ether  by  distillation,  and  transfer  the  residue  into  a  platinum  crucible 
by  means  of  a  small  amount  of  ether.  Evaporate  the  ether  on  a  steam  bath,  add 
about  2-3  cc.  of  10%  sodium  carbonate  solution  to  the  residue,  rotate  so  that  all 
of  the  residue  is  brought  into  contact  with  the  solution,  and  evaporate  to  dryness 
on  a  steam  bath.  Add  4  grams  of  a  mixture  of  equal  parts  of  anhydrous  sodium  and 
potassium  carbonates,  heat  gently  at  first,  and  then  to  complete  fusion  for  30  minutes 
over  an  alcohol  or  other  sulphur-free  flame.  Cool,  dissolve  the  melt  in  water,  acidify 
with  hydrochloric  acid  and  determine  the  sulphate  present  as  barium  sulphate. 
Correct  the  result  thus  obtained  for  any  sulphur  present  in  the  fusion  mixture  as 
found  in  a  blank  determination.  Calculate  the  amount  of  saccharin  in  the  sample 
by  multiplying  the  weight  of  barium  sulphate  by  0.7845. 

BORIC  ACID  AND  BORATES. 

14  Qualitative   Test.^ 

Preliminary  test. — Immerse  a  strip  of  turmeric  paper  in  the  sample  acidified 
with  hydrochloric  acid  in  the  proportion  of  7  cc.  of  concentrated  acid  to  each  100 
cc.  of  sample,  and  allow  the  paper  to  dry  spontaneously.  If  borax  or  boric  acid  is 
present,  the  paper  will  acquire  a  peculiar  red  color,  changed  by  ammonium  hydroxid 
to  a  dark  blue-green  but  restored  by  acid.  Solid  or  pasty  samples  may  be  heated 
with  enough  water  to  make  them  sufficiently  fluid,  concentrated  hydrochloric  acid 
added  in  about  the  proportion  of  1  to  13  and  the  liquid  tested  in  the  same  way. 

Confirmatory  test. — Make  about  25  grams  of  the  sample  decidedly  alkaline  with 
lime  water  and  evaporate  to  dryness  on  a  water  bath.  Ignite  the  residue  to  de- 
stroy organic  matter.  Digest  with  about  15  cc.  of  water,  add  concentrated  hydro- 
chloric acid,  drop  by  drop,  until  the  ignited  residue  is  dissolved,  and  then  add  1  cc. 
in  excess.  Saturate  a  piece  of  turmeric  paper  with  the  solution,  and  allow  it  to 
dry  without  the  aid  of  heat.  In  the  presence  of  borax  or  boric  acid,  the  color  change 
will  be  the  same  as  given  above. 

15  Quantitative  Method.* 

Make  10-100  grams  of  the  sample  (depending  upon  the  nature  of  the  sample 
and  the  amount  of  boric  acid  present)  distinctly  alkaline  with  sodium  hydroxid 
solution  and  evaporate  to  dryness  in  a  platinum  dish.  Ignite  the  residue  until 
organic  matter  is  destroyed,  avoiding  an  intense  red  heat,  cool,  digest  with  about 
20  cc.  of  hot  water,  and  add  hydrochloric  acid,  drop  by  drop,  until  the  reaction  is 
distinctly  acid.  Filter  into  a  100  cc.  flask,  and  wash  with  a  little  hot  water,  the 
volume  of  the  filtrate  not  to  exceed  50-60  cc.  Return  the  filter  containing  any 
unburned  carbon  to  the  platinum  dish,  make  alkaline  by  wetting  thoroughly  with 
lime  water,  dry  on  a  steam  bath  and  ignite  to  a  white  ash.  Dissolve  the  ash  in 
a  few  cc.  of  dilute  hydrochloric  acid  and  add  to  the  liquid  in  the  100  cc.  flask,  rins- 
ing the  dish  with  a  few  cc.  of  water.  To  the  combined  solutions,  add  0.5  gram  of 
calcium  chlorid  and  a  few  drops  of  phenolphthalein,  then  10%  sodium  hydroxid 
solution   until    a   permanent  light   pink   color   is   produced,    and  finally  dilute  to 


X]  FOOD   PRESERVATIVES  147 

the  mark  with  lime  water.  Mix  and  filter  through  a  dry  filter.  To  50  cc.  of  the 
filtrate  add  N/1  sulphuric  acid  until  the  pink  color  disappears,  then  add  methyl 
orange,  and  continue  the  addition  of  the  acid  until  the  yellow  color  is  changed  to 
pink.  Boil  for  about  1  minute  to  expel  carbon  dioxid.  Cool,  and  carefully  add 
N/5  sodium  hydroxid  until  the  liquid  assumes  a  yellow  tinge,  avoiding  an  excess 
of  the  alkali.  All  the  boric  acid  is  now  in  a  free  state  with  no  uncombined  sulphuric 
acid  present.  Add  a  little  phenolphthalein,  and  an  equal  volume  of  neutral  glycerol. 
Titrate  with  N/5  sodium  hydroxid  until  a  permanent  pink  color  is  produced.  About 
10  grams  of  mannitol  may  be  substituted  for  the  glycerol  in  this  determination. 
At  the  end  of  the  titration  add  an  additional  2  grams  and  continue  the  titration  if 
the  pink  color  is  discharged.  Repeat  the  alternate  addition  of  mannitol  and  alkali 
until  a  permanent  end  point  is  reached. 

One  cc.  of  N/5  sodium  hydroxid  is  equivalent  to  0.0124  gram  of  boric  acid. 

FORMALDEHYDE. 

16  PREPARATION  OF  SAMPLE. 

If  solid  or  semi-solid,  macerate  200-300  grams  of  the  material  with  about  100  cc. 
of  water  in  a  mortar.  Transfer  to  a  short-necked,  500-800  cc.  copper  or  glass  dis- 
tillation flask  and  make  distinctly  acid  with  phosphoric  acid,  connect  with  a  con- 
denser and  distil  40-50  cc.  In  the  case  of  highly  colored  liquids,  the  same  method 
of  preparation  should  be  employed. 

In  the  case  of  meats  and  fats,  extract  the  formaldehyde  with  alcohol  and  use  the 
filtrate.  In  the  case  of  fat,  heat  the  mixture  above  the  melting  point  of  the  fat  to 
insure  thorough  extraction.  In  the  case  of  milk,  shake  with  an  equal  volume  of 
strong  alcohol  and  use  the  filtrate.  Shake  other  liquids  with  an  equal  volume  of 
strong  alcohol  and  filter  from  any  insoluble  matter. 

QUALITATIVE  TESTS. 

17  Phenylhydrazin  Hydrochlorid  Method.^ 

Mix  5  cc.  of  the  distillate,  as  prepared  under  16,  or  of  an  alcoholic  solution  or 
extract  obtained  as  directed  above,  with  0.03  gram  of  phenylhydrazin  hydrochlorid, 
and  4  or  5  drops  of  a  1%  ferric  chlorid  solution.  Add  slowly  and  with  agitation, 
in  a  bath  of  cold  water  to  prevent  heating  the  liquid,  1-2  cc.  of  concentrated  sul- 
phuric acid.  Dissolve  the  precipitate  by  the  addition  either  of  concentrated  sul- 
phuric acid  (keeping  the  mixture  cool)  or  alcohol.  In  the  presence  of  formaldehyde 
a  red  color  develops. 

This  method  gives  reliable  reactions  for  formaldehyde  in  solutions  of  formalde- 
hyde varying  from  1  part  in  50,000  to  1  part  in  150,000.  Acetaldehyde  and  benz- 
aldehyde  give  no  reaction  when  treated  by  this  method  and  do  not  interfere  with 
the  reaction  given  by  formaldehyde. 

18  II ehner  Method.^ 

Mix  about  5  cc.  of  the  distillate,  obtained  in  16,  with  an  equal  volume  of  pure 
milk,  or  a  1-2%  solution  of  egg  albumen,  in  a  test  tube  and  underlay  with  strong 
commercial  sulphuric  acid  without  mixing.  A  violet  or  blue  color  at  the  junction 
of  the  two  liquids  indicates  formaldehyde.  This  color  is  given  only  in  the  presence 
of  a  trace  of  ferric  chlorid  or  other  oxidizing  agent.  As  pointed  out  by  Hehner, 
milk  may  be  treated  directJy  by  this  method  and  gives  positive  tests  in  the  presence 
of  1  or  more  parts  of  formaldehyde  per  10,000.  Some  other  articles  of  food  rich 
in  proteins,  for  example,  egg  albumen,  give  the  reaction  in  the  presence  of  water 
without  the  addition  of  milk. 


148  METHODS   OF   ANALYSIS  [Chap. 

1 9  Leach  Method. 

Mix  about  5  cc.  of  the  distillate,  obtained  under  16,  with  an  equal  volume  of  pure 
milk  in  a  porcelain  casserole  and  add  about  10  cc.  of  concentrated  hydrochloric 
acid,  containing  1  cc.  of  10%  ferric  chlorid  solution,  to  each  500  cc.  of  acid.  Heat 
to  80°-90°C.  directly  over  the  gas  flame,  rotating  the  casserole  to  break  up  the  curd. 
A  violet  coloration  indicates  formaldehyde. 

Rimini  Method.'' 

20  Phenylhydrazin  Hydrochlorid  and  Sodium  Nitro-prussid  Test. 

This  method  may  be  applied  directly  to  liquid  foods,  to  an  aqueous  or  alcoholic 
extract  of  solid  foods,  or  to  the  distillate  prepared  as  directed  in  16.  In  the  case 
of  milk,  apply  the  method  directly.  In  the  case  of  meat,  comminute  the  sample, 
extract  with  2  volumes  of  hot  water,  and  employ  the  expressed  liquid  for  the  test. 
Heat  fats  above  their  melting  point  with  10  cc.  of  alcohol,  shake  thoroughly,  cool, 
filter  through  a  moistened  filter,  and  use  the  filtrate  for  the  test. 

Dissolve  a  lump  of  phenylhydrazin  hydrochlorid  about  the  size  of  a  pea  in  3-5 
cc.  of  the  liquid  to  be  tested,  add  2-4  drops  (not  more)  of  a  5-10%  sodium  nitro- 
prussid  solution  and  8-12  drops  of  an  approximately  12%  sodium  hydroxid  solution. 
If  formaldehyde  is  present,  a  green  or  blue  color  develops  depending  upon  the 
amount.  When  formaldehyde  is  present  to  the  extent  of  more  than  1  part  in  70,000- 
80,000  in  the  solution  tested,  a  distinct  green  or  bluish  green  reaction  is  obtained. 
In  more  dilute  solutions  the  green  tint  becomes  less  marked  and  a  yellow  tinge  tend- 
ing toward  greenish  brown  develops. 

With  this  method  acetaldehyde  and  benzaldehyde  give  a  color  varying  from 
red  to  brown,  according  to  the  strength  of  the  solution.  A  reaction  may  there- 
fore be  obtained  with  these  aldehydes  similar  to  that  obtained  with  formaldehyde 
in  solutions  more  dilute  than  1  part  in  70,033.  The  presence  of  acetaldehyde  or 
benzaldehyde  together  with  formaldehyde  gives  a  yellowish  or  yellowish  green 
tinge.  The  reaction  for  formaldehyde  may  therefore  be  masked  by  the  presence 
of  other  aldehydes,  but  is  characteristic  when  a  clear  green  color  is  obtained. 

21  Phenylhydrazin  Hydrochlorid  and  Potassium  Ferricyanid  Test. 

Proceed  as  directed  in  20,  substituting  a  solution  of  potassium  ferricyanid  for 
the  sodium  nitro-prussid.  Formaldehyde  gives  a  red  color.  Alcoholic  extracts 
from  foods  must  be  diluted  with  water  to  prevent  the  precipitation  of  potassium 
ferricyanid.  The  test  is  not  applicable  in  the  presence  of  the  coloring  matter  of 
blood. 

22  Phenylhrjdrazin  Hydrochlorid  and  Ferric  Chlorid  Test. 

Treat  15  cc.  of  milk  or  other  liquid  food  or  of  the  distillate,  prepared  as  directed 
under  16,  with  1  cc.  of  a  dilute  phenylhydrazin  hydrochlorid  solution,  then  with 
a  few  drops  of  dilute  ferric  chlorid  solution  and,  finally,  with  concentrated  hydro- 
chloric acid.  The  presence  of  formaldehyde  is  indicated  by  the  formation  of  a 
red  color,  which  changes  after  some  time  to  orange  yellow. 

Milk  may  be  examined  directly  by  this  method,  but  more  delicate  tests  may  be 
obtained  from  the  distillate  from  milk  or  from  milk  serum.  Acetaldehyde  or  benz- 
aldehyde does  not  interfere  with  the  reaction. 


X]  FOOD    PRESERVATIVES  149 

23  Phloroglucol  Method.^ 

To  10  cc.  of  milk  or  other  liquid  food  under  examination  in  a  test  tube  add,  by 
means  of  a  pipette,  2  cc.  of  phloroglucol  reagent  (1  gram  of  phloroglucol,  20  grams  of 
sodium  hydroxid  and  water  to  make  100  cc),  placing  the  end  of  the  pipette  on  the 
bottom  of  the  tube  in  such  a  manner  that  the  reagent  will  form  a  separate  layer. 

If  formaldehyde  be  present,  a  bright  red  coloration  (not  purple)  forms  at  the 
zone  of  contact.  This  solution  gives  a  yellow  color  in  the  presence  of  some  alde- 
hydes, and,  if  it  is  used  for  the  detection  of  aldehyde  formed  by  the  oxidation  of 
methyl  alcohol  after  the  destruction  of  ethyl  aldehyde  with  hydrogen  peroxid,  an 
orange  yellow  color  will  slowly  appear  when  an  insufficient  amount  of  hydrogen 
peroxid  has  been  employed.  On  the  other  hand,  if  the  excess  of  hydrogen 
peroxid  is  not  fully  destroyed  before  the  use  of  this  reagent,  a  purple  color  develops 
slowly.  The  clear,  red  color  given  by  the  use  of  this  reagent  forms  quickly,  and, 
in  the  presence  of  but  a  small  amount  of  formaldehyde  fades  rapidly. 

FLUORIDS. 

QUALITATIVE  TESTS. 

24  Method  I. —Modified  Method  of  Blarez.^ 

Thoroughly  mix  the  sample  and  boil  150  cc.  (in  the  case  of  solid  foods  an  aqueous 
extract  may  be  employed  provided  the  fluorids  are  in  a  soluble  form).  Add  to  the 
boiling  liquid  5  cc.  of  10%  potassium  sulphate  solution  and  10  cc.  of  10%  barium 
acetate  solution.  Collect  the  precipitate  in  a  compact  mass  (a  centrifuge  may  be 
used  advantageously)  and  wash  upon  a  small  filter.  Transfer  to  a  platinum  crucible 
and  ignite. 

Dip  a  carefully  cleaned  glass  plate,  while  hot,  in  a  mixture  of  equal  parts  of  Car- 
naiiba  wax  and  paraffin  and  allow  to  cool.  Make,  with  a  sharp  instrument,  a  dis- 
tinctive mark  through  the  wax,  taking  care  not  to  scratch  the  surface  of  the  glass. 

Add  a  few  drops  of  concentrated  sulphuric  acid  to  the  residue  in  the  crucible 
and  cover  with  the  waxed  plate,  having  the  mark  nearly  over  the  center  and  mak- 
ing sure  that  the  edge  of  the  crucible  is  in  close  contact  with  it.  Keep  the  top  sur- 
face of  the  plate  cool  by  means  of  a  suitable  device  and  heat  the  crucible  for  an  hour 
at  as  high  a  temperature  as  practicable  without  melting  the  wax  (an  electric  stove 
gives  the  most  satisfactory  form  of  heat). 

If  fluorids  be  present,  a  distinct  etching  will  be  apparent  on  the  glass  where  it 
was  exposed. 

25  Method  II. 

The  preceding  method  may  be  varied  by  mixing  a  small  amount  of  precipitated 
silica  with  the  precipitated  barium  fluorid  and  applying  the  method  for  the  detection 
of  fluosilicates,  under  27  or  28. 

This  method  is  of  value  in  the  case  of  foods  whose  ash  contains  a  considerable 
amount  of  silica.  Under  these  circumstances,  concentrated  sulphuric  acid  liber- 
ates silicon  fluorid,  which  would  escape  detection  under  24. 

FLUOBORATES  AND  FLUOSILICATES. 

26  PREPARATION  OF  SAMPLE. 

Make  about  200  grams  of  the  sample  alkaline  with  lime  water,  evaporate  to  dry- 
ness, and  incinerate.     Extract  the  crude  ash  with  water,  to  which  sufficient  acetic 


150  METHODS    OF   ANALYSIS  [Chap. 

acid  has  been  added  to  decompose  carbonates,  filter,  ignite  the  insoluble  portion, 
extract  with  dilute  acetic  acid,  and  again  filter.  The  insoluble  portion  now  con- 
tains calcium  silicate  and  fluorid,  while  the  filtrate  will  contain  all  the  boric  acid 
present. 

QUALITATIVE    TESTS. 

27  Method  7.1° 

Incinerate  the  filter,  from  26,  containing  the  insoluble  portion,  mix  with  a  little 
precipitated  silica,  transfer  to  a  short  test  tube,  attached  to  a  small  U-tube  contain- 
ing a  few  drops  of  water  and  add  1-2  cc.  of  concentrated  sulphuric  acid.  Keep 
the  test  tube  in  a  beaker  of  water  on  the  steam  bath  for  30-40  minutes.  If  any 
fluorin  be  present,  the  silicon  fluorid  generated  will  be  decomposed  by  the  water 
in  the  U-tube  and  will  form  a  gelatinous  deposit  on  the  walls  of  the  tube. 

Next  test  the  filtrate  as  directed  under  14.  If  both  hydrofluoric  and  boric  acids 
be  present,  it  is  probable  that  they  are  combined  as  borofluorid.  If,  however, 
silicon  fluorid  is  detected  and  not  boric  acid,  the  operation  should  be  repeated  with- 
out the  introduction  of  the  silica,  in  which  case  the  formation  of  the  silicon  skeleton 
is  conclusive  evidence  of  the  presence  of  fluosilicate.  In  an  ash  containing  an  ap- 
preciable amount  of  silica,  sulphuric  acid  will  liberate  silicon  fluorid  rather  than 
hydrofluoric  acid.  The  presence  of  a  fluosilicate  is  indicated,  therefore,  and  not 
the  presence  of  a  fluorid. 

28  Method  II. 

Incinerate  the  filter,  from  26,  containing  the  insoluble  portion,  in  a  platinum 
crucible,  mix  with  a  little  precipitated  silica,  and  add  1  cc.  of  concentrated  sul- 
phuric acid.  Cover  the  crucible  with  a  watch  glass,  from  the  underside  of  which 
a  drop  of  water  is  suspended,  and  heat  for  an  hour  at  70°-80°C.,  keeping  the  watch 
glass  cooled.  The  silicon  fluorid  which  is  formed  is  decomposed  by  the  water,  leav- 
ing a  gelatinous  deposit  of  silica  and  etching  a  ring  at  the  periphery  of  the  drop 
of  water.     Test  the  filtrate  for  boric  acid  as  directed  under  14. 

SULPHUROUS  ACID. 

29  Qualitative   Test.^^ 

Add  some  sulphur-free  zinc,  and  several  cc.  of  hydrochloric  acid  to  about  25 
grams  of  the  sample  (with  the  addition  of  water,  if  necessary)  in  a  200  cc.  Erlen- 
meyer  flask.  In  the  presence  of  sulphites,  hydrogen  sulphid  will  be  generated 
and  may  be  detected  with  lead  acetate  paper.  Traces  of  metallic  sulphids  are 
occasionally  present  in  vegetables,  and  will  give  the  same  reaction  as  sulphites 
under  the  conditions  of  the  above  test.  Positive  results  obtained  by  this  method 
should  be  verified  by  the  distillation  method  under  30. 

It  is  always  advisable  to  make  the  quantitative  determination  of  sulphites, 
owing  to  the  danger  that  the  test  may  be  due  to  traces  of  sulphids.  A  trace  is  not 
to  be  considered  sufficient  indication  of  the  presence  of  sulphur  dioxid  either  as  a 
bleaching  agent  or  as  a  preservative. 

TOTAL  SULPHUROUS  ACID. 

30  Method  I. — Distillation  Method. 

Distil  20-100  grams  of  the  sample  (adding  recently  boiled  water  if  necessary) 
in  a  current  of  carbon  dioxid,  after  the  addition  of  about  5  cc.  of  a  20%  glacial  phos- 


X]  FOOD    PRESERVATIVES  151 

phoric  acid  solution,  until  150  cc.  have  passed  over.  Collect  the  distillate  in  about 
100  cc.  of  nearly  saturated  bromin  water,  allowing  the  end  of  the  condenser  to  dip 
below  the  surface.  The  method  and  apparatus  may  be  simplified  without  material 
loss  in  accuracy  by  omitting  the  current  of  carbon  dioxid,  adding  10  cc.  of  phosphoric 
acid  instead  of  5  cc,  and  dropping  into  the  distillation  flask,  immediately  before 
attaching  the  condenser,  a  piece  of  sodium  bicarbonate  weighing  not  more  than 
1  gram.  The  carbon  dioxid  liberated  is  not  sufficient  to  expel  the  air  entirely  from 
the  apparatus,  but  will  prevent  oxidation  to  a  large  extent.  When  the  distillation 
is  finished,  boil  off  the  excess  of  bromin,  dilute  the  solution  to  about  250  cc,  add  5 
cc.  of  hydrochloric  acid  (1  to  3),  heat  to  boiling,  and  precipitate  the  sulphuric  acid 
with  10%  barium  chlorid  solution.  Boil  for  a  few  minutes  longer,  allow  to  stand 
overnight  in  a  warm  place,  filter  on  a  weighed  Gooch,  wash  with  hot  water,  ignite 
at  a  dull  red  heat,  and  weigh  as  barium  sulphate. 

31  Method  II.— Direct  Titration  Method. 

In  the  examination  of  wine,  fairly  accurate  results  may  be  obtained  by  the  fol- 
lowing method : 

Place  25  cc.  of  5.6%  potassium  hydroxid  solution  in  a  200  cc.  flask.  Introduce 
50  cc.  of  the  sample,  mix  with  the  potassium  hydroxid  solution,  and  allow  the  mix- 
ture to  stand  for  15  minutes  with  occasional  agitation.  Add  10  cc.  of  sulphuric  acid 
(1  to  3)  and  a  few  cc.  of  starch  solution,  and  titrate  the  mixture  with  N/50  iodin  solu- 
tion. Introduce  the  iodin  solution  as  rapidly  as  possible  and  continue  the  addition 
until  the  blue  color  persists  for  several  minutes.  One  cc.  of  N/50  iodin  is  equiva- 
lent to  0.00064  gram  of  sulphur  dioxid. 

DETERMINATION  OF  FREE  SULPHUROUS  ACID, 

32  (Especially  Adapted  to  Wine.) 

Treat  50  cc.  of  the  sample  in  a  200  cc.  flask  with  about  5  cc.  of  sulphuric  acid 
(1  to  3)  add  about  0.5  gram  of  sodium  carbonate  to  expel  the  air,  and  titrate  the  sul- 
phurous acid  with  N/50  iodin,  as  directed  under  31. 

BETA-NAPHTHOL. 

33  Qualitative   Test. 

Extract  200  cc.  of  the  sample,  or  of  its  aqueous  extract,  prepared  as  directed 
under  1  (C),  with  10  cc  of  chloroform  in  a  separatory  funnel.  To  the  chloroform 
extract  in  a  test  tube  add  a  few  drops  of  alcoholic  potash,  and  place  in  a  boiling 
water  bath  for  2  minutes.  The  presence  of  beta-napthol  is  indicated  by  the  forma- 
tion of  a  deep  blue  color,  which  changes  to  green  and  then  to  yellow. 

ABRASTOL. 

QUALITATIVE  TESTS. 

34  Sinibaldi  Method.^* 

Make  50  cc.  of  the  sample  alkaline  with  a  few  drops  of  ammonium  hydroxid  and 
extract  with  10  cc.  of  amyl  alcohol,  adding  ethyl  alcohol  if  an  emulsion  is  formed. 
Decant  the  amyl  alcohol,  filter  if  turbid,  and  evaporate  to  dryness.  Add  to  the 
residue  2  cc.  of  nitric  acid  (1  to  1),  heat  on  the  water  bath  until  half  of  the  liquid 
is  evaporated,  and  transfer  to  a  test  tube  with  the  addition  of  1  cc.  of  water.  Add 
about  0.2  gram  of  ferrous  sulphate  and  an  excess  of  ammonium  hydroxid,  drop  by 


152  METHODS   OF   ANALYSIS  [Chap. 

drop,  with  constant  shaking.  If  the  resultant  precipitate  is  of  a  reddish  color, 
dissolve  it  in  a  few  drops  of  sulphuric  acid,  and  add  ferrous  sulphate  and  ammonium 
hydroxid  as  before.  As  soon  as  a  dark  colored  or  greenish  precipitate  is  obtained, 
introduce  5  cc.  of  alcohol,  dissolve  the  precipitate  in  sulphuric  acid,  shake  well  and 
filter.  In  the  absence  of  abrastol  this  method  gives  a  colorless  or  light  yellow  liquid, 
while  a  red  color  is  produced  in  the  presence  of  0.01  gram  of  abrastol. 

35  Sangle-Ferriere  Method." 

Boil  200  cc.  of  the  sample  with  8  cc.  of  concentrated  hydrochloric  acid  for  an 
hour  in  a  flask  fitted  with  a  reflux  condenser.  Abrastol  is  thus  converted  into  beta- 
naphthol  and  is  detected  as  directed  under  33. 

SUCROL  OR  DULCIN. 
QUALITATIVE  TESTS. 

36  M  or  pur  go  Method.^* 

Evaporate  about  100  cc.  of  the  sample,  or  of  the  aqueous  extract  prepared  as 
directed  under  1  (C)  and  neutralized  with  acetic  acid,  to  a  sirupy  consistency  after 
the  addition  of  about  5  grams  of  lead  carbonate,  and  extract  the  residue  several 
times  with  90%  alcohol.  Evaporate  the  alcoholic  extract  to  dryness,  extract  the 
residue  with  ether,  and  allow  the  ether  to  evaporate  spontaneously  in  a  porcelain 
dish.  Add  2  or  3  drops  each  of  phenol  and  concentrated  sulphuric  acid  and  heat 
for  about  5  minutes  on  the  water  bath,  cool,  transfer  to  a  test  tube  and  overlay  with 
ammonium  hydroxid  or  sodium  hydroxid  solution  with  the  least  possible  mixing. 
The  presence  of  dulcin  is  indicated  by  the  formation  of  a  blue  color  at  the  zone  of 
contact. 

37  Jorissen  Method.^^ 

Suspend  the  residue  from  the  ether  extract  obtained  as  directed  above  in  about 
5  cc.  of  water;  add  2-4  cc.  of  an  approximately  10%  solution  of  mercuric  nitrate, 
and  heat  for  5-10  minutes  on  the  water  bath.  In  the  presence  of  sucrol  a  violet  blue 
color  is  formed,  which  is  changed  to  a  deep  violet  on  the  addition  of  lead  peroxid. 

FORMIC  ACID. 

Quantitative  Method. ^^ 

38  REAGENTS. 

(a)  Sodium  acetate  solution.— Dissolve  50  grams  of  dry  sodium  acetate  in  sufl5- 
cient  water  to  make  100  cc.  and  filter. 

(b)  Mercuric  chlorid  reagent. — Dissolve  100  grams  of  mercuric  chlorid  and  150 
grams  of  sodium  chlorid  in  sufficient  water  to  make  1  liter  and  filter. 

(C)  Tartaric  acid. 

(d)  Barium  carbonate. 

39  APPARATUS. 

The  apparatus  required  (Fig.  6)  consists  of  a  steam  generator  (S),  a  300  cc.  flask 
(A)  in  which  the  sample  is  placed,  a  500  cc.  flask  {B),  containing  a  suspension  of  bari- 
um carbonate,  a  spray  trap  (T),  a  condenser,  and  a  1  liter  graduated  flask  (C). 
The  tip  of  the  tube  (D),  leading  into  (fi),  consists  of  a  bulb  containing  a  number 
of  small  holes  to  break  the  vapor  into  small  bubbles. 


X] 


FOOD    PRESERVATIVES 


153 


FIG.  6.    APPARATUS  FOR  DETECTION  OF  FORMIC  ACID. 


40  DETERMINATION. 

For  thin  liquids  like  fruit  juices,  use  50  cc.  For  heavy  liquids  and  semi-solids 
like  sirups  and  jams,  use  50  grams  diluted  with  50  cc.  of  water.  Place  the  sam- 
ple in  the  flask  (A),  add  1  gram  of  tartaric  acid,  and  connect  as  shown  in  Fig.  6, 
the  flask  (B)  having  been  charged  previously  with  a  suspension  of  2  grams  of  barium 
carbonate  in  100  cc.  of  water.  If  much  acetic  acid  is  present,  suflficient  barium 
carbonate  must  be  used  so  that  at  least  1  gram  remains  at  the  end  of  the  operation. 
Heat  the  contents  of  flasks  (.1)  and  (B)  to  boiling  and  distil  with  steam  from  the 
generator  (5),  the  vapor  passing  first  through  the  sample  in  flask  {A),  then  through 
the  boiling  suspension  of  barium  carbonate  in  (B),  after  which  it  is  condensed,  and 
measured  in  the  graduated  flask  (C).  Continue  the  distillation  until  1  liter  of  dis- 
tillate is  collected,  maintaining  the  volume  of  the  liquids  in  the  flasks  {A)  and  (B) 
as  nearly  constant  as  possible  by  heating  with  small  Bunsen  flames,  and  avoid- 
ing charring  of  the  sample  in  the  flask  {A).  After  1  liter  of  distillate  has  been  col- 
lected, disconnect  the  apparatus  and  filter  the  contents  of  flask  (B)  while  hot,  wash- 
ing the  barium  carbonate  with  a  little  hot  water.  The  filtrate  and  washings  should 
now  measure  about  150  cc.  If  not  they  should  be  boiled  down  to  that  volume.  Then 
add  10  cc.  of  the  sodium  acetate,  2  cc.  of  10%  hydrochloric  acid,  and  25  cc.  of  the 
mercuric  chlorid  reagent.  Mix  thoroughly  and  immerse  the  container  in  a  boil- 
ing water  bath  or  steam  bath  for  2  hours.  Then  filter  on  a  tared  Gooch,  wash  the 
precipitate  thoroughly  with  cold  water  and  finally  with  a  little  alcohol.  Dry  in  a 
boiling  water  oven  for  30  minutes,  cool,  weigh,  and  calculate  the  weight  of  formic 
acid  present  by  multiplying  the  weight  of  the  precipitate  by  0.0975.  If  the  weight 
of  mercurous  chlorid  obtained  exceeds  1.5  grams,  the  determination  must  be  re- 
peated, using  more  mercuric  chlorid  reagent  or  a  smaller  amount  of  sample.    A  blank 


154  METHODS   OF   ANALYSIS 

test  should  be  conducted  with  each  new  lot  of  reagents  employed  in  the  reduction, 
using  150  cc.  of  water,  1  cc.  of  10%  barium  chlorid  solution,  2  cc.  of  10%  hydrochloric 
acid,  10  cc.  of  the  sodium  acetate,  and  25  cc.  of  the  mercuric  chlorid  reagent,  heat- 
ing the  mixture  in  a  boiling  water  bath  or  steam  bath  for  2  hours.  The  weight  of 
mercurous  chlorid  obtained  in  this  blank  test  must  be  deducted  from  that  obtained 
in  the  regular  determination. 

BIBLIOGRAPHY. 

1  J.  Ind.  Eng.  Chem.,  1910,  2:  24. 

2  Z.  Nahr.  Genussm.,  1910, 19:  137;  C.  A.,  1910,  4:  1523. 

3  U.  S.  Div.  Chem.  Bull.  51,  p.  113. 

*  Sutton.     Volumetric  Analysis.  10th  ed.,  1911,  p.  95. 
6  Z.  Nahr.  Genussm.,  1902,  5:  353. 

6  Analyst,  1895,  20:  155. 

7  Ann.  di  farmacoterapia  e  chim.,  1898,  27:  97;  Chem.  Zentr.,  1898,  (1),  1152;  1902, 
(1),  1076;  J.  Soc.  Chem.  Ind.,  1898,  17:  697;  Chem.  Ztg.,  1902,  26:  246;  Abs.  J.  Chem. 
Soc,  1902,  82:  367. 

*  Service  de  Surveillance  des  Aliments  en  Belgique,  through  Bui.  soc.  chim.  belg., 
1897-8,  11-12:  211;  Abs.  Analyst,  1897,  22:  282. 

9  Chem.  News,  1905,  91:  39;  Ann.  Rept.  Mass.  State  Board  of  Health,  1905,  p.  498 

i«Mon.  Sci.,  1895,  (4),  9:  324. 

"  U.  S.  Div.  Chem.  Bull.  13,  (8),  p.  1032. 

12  Mon.  Sci.,  1893,  (4),  7:  842. 

'3  Compt.  rend.,  1893,  117:  796. 

'*  Z.  anal.  Chem.,  1896,  35:  104 

"  Ibid.,  628. 

'«  Biochem.  Z.,  1913,  51:  253. 


XI.    COLORING  MATTERS  IN  FOODS.— TENTATIVE. 

(An  italicized  number,  following  immediately  the  name  of    a  dye,  is  the 

number  by  which  that  dye  is  designated  in  "A  Systematic  Survey  of 

the  Organic  Colouring  Matters",  1904,  by  Arthur  Green, 

based   on    the   German    of   Schultz    and   Julius.) 

1  PIGMENTS. 

The  insoluble  pigments,  ultramarine,  lampblack,  etc.,  are  most  commonly  used 
as  facings  and  may  be  separated  by  washing  the  sample  with  water  and  allowing 
the  washings  to  settle.  The  particles  of  coloring  matter  can  be  identified  by  micro- 
scopic examination  and  by  treatment  of  the  residue  or  purified  coloring  matter 
with  chemical  reagents.  A  large  proportion  of  the  common  pigments  other  than 
lakes,  such  as  the  yellow,  brown  and  red  ochres  and  umbers,  are  derivatives  of  the 
heavy  metals  and  contain  iron,  manganese,  etc.  Others,  such  as  various  green  and 
blue  compounds,  including  the  green  chlorophyll  derivatives,  contain  copper. 
These  pigments  may  be  identified  by  the  usual  tests  for  the  respective  metals.  The 
analytical  properties  of  the  insoluble  coloring  matters  are  described  in  various 
standard  works,  some  of  which  are  listed  in  the  bibliography,  especially  "Farb- 
stofftabellen  by  Schultz'." 

Soluble  Coloring  Matters  and  Their  Lakes, 
coal  tar  dyes. 

2  Wool  dyeing  test^. 

(a)  WiJies,  fruit  juices,  distilled  liquors,  flavoring  extracts,  vinegars,  beers,  sirups, 
non-alcoholic  beverages  and  similar  products. — Dilute  20-200  cc.  of  the  sample  with 
1-3  volumes  of  water  and  boil  or  heat  on  the  steam  bath  with  a  small  piece  of  white 
woolen  cloth  (nun's  veiling).  When  the  mixture  contains  much  alcohol,  heat  until 
most  of  the  alcohol  has  been  removed;  in  other  cases,  take  out  the  wool  after 
5-15  minutes  and  rinse  with  water.  Then  treat  the  liquid  with  3  or  4  drops  of  con- 
centrated hydrochloric  acid  for  each  100  cc.  and  warm  again  for  10-20  minutes  with 
a  clean  piece  of  wool.  The  basic  dyes  go  on  the  fiber  best  from  neutral  or  faintly 
ammoniacal  solutions  and,  if  present,  will  appear  on  the  first  piece  of  wool.  Acid 
colors  dye  from  neutral  solutions  but  more  readily  from  those  containing  free  acid. 
If  the  wool  takes  up  any  considerable  amount  of  coloring  matter  in  either  case,  the 
presence  of  coal  tar  dyes  is  indicated.  The  lichen  colors'  (Archil,  Cudbear,  Litmus) 
go  readily  on  wool,  however,  and  many  other  natural  colors,  such  as  Turmeric,  will 
dye  the  fiber,  if  present  in  considerable  amount.  On  the  other  hand,  a  few  coal 
tar  dyes,  especially  Auramine  O  and  Naphthol  Green  B,  are  quite  unstable  and,  if 
present  in  small  amounts,  may  give  no  distinct  dyeing.  Acid  dyes  are  much  more 
frequently  used  than  basic  dyes  and  in  most  cases  may  be  removed  from  wool  with- 
out much  decomposition  by  "stripping"  the  latter  with  dilute  ammonia^  By  the 
action  of  the  alkali,  many  natural  colors  are  destroyed,  while  others  remain  for  the 
most  part  on  the  fiber.  If  the  behavior  with  wool  in  neutral  and  acid  solutions 
indicates  the  presence  of  acid  dyes,  rinse  the  colored  cloth  thoroughly  with  water, 
cover  with  2%  ammonium  hydroxid  solution  in  a  casserole,  boil  for  a  few  minutes, 
remove  the  cloth  and  squeeze  out  the  adhering  liquid.     Boil  the  ammoniacal  solu- 

155 


156  METHODS    OF   ANALYSIS  [Chap. 

tion  to  remove  the  excess  of  ammonia,  drop  in  a  piece  of  clean,  wet  wool,  make  dis- 
tinctly but  not  strongly  acid  with  hydrochloric  acid  and  boil  again.  If  acid  coal 
tar  dyes  are  present,  they  will  usually  give  a  fairly  clean,  bright  dyeing  on  the  second 
piece  of  wool.  A  further  purification  may  be  carried  out  by  repeating  the  stripping 
and  re-dyeing,  though  generally  accompanied  by  corresponding  loss  of  dye. 

(b)  Candies  and  similar  colored  sugar  products. — Dissolve  about  20  grams  of  the 
sample  in  100  cc.  of  water  and  treat  the  solution  as  directed  under  (a).  When  the 
coloring  matter  is  on  the  surface  of  the  candy,  pour  off  the  solution  before  the  color- 
less inner  portion  has  dissolved. 

(C)  Jams  and  jellies. — Boil  a  mixture  of  10-20  grams  of  the  sample  and  100  cc. 
of  water  with  wool  in  neutral  and  also  in  acid  solution  as  directed  under  (a).  For 
thick  jams  it  is  usually  better,  though  less  easy,  first  to  extract  the  coloring  sub- 
stances by  treating  the  product  as  directed  under  (d). 

(d)  Canned  and  preserved  fruits  and  vegetables,  sausage  casings,  smoked  fish,  coffee, 
spices,  etc. — Macerate  20-200  grams  of  the  sample  with  4-5  times  its  weight  of  80% 
alcohol.  After  standing  a  few  hours  pour  off  the  solvent  as  completely  as  possible 
and  repeat  the  extraction,  using  70%  alcohol  containing  about  1%  of  ammonia. 
(1)  Examine  separately  the  filtered  alcoholic  extracts  as  directed  under  (a);  or,  (2) 
Boil  the  ammoniacal  solution  until  practically  neutral,  complete  the  neutralization 
with  acetic  acid,  add  the  neutral  80%  alcohol  extract,  continue  the  evaporation 
until  most  of  the  alcohol  is  removed,  and  boil  with  wool  as  directed  under  (a). 

(e)  Cocoa  and  chocolate  products. — Treat  cocoa  as  directed  under  (d).  The  alco- 
holic extract  will  contain  a  large  amount  of  natural  coloring  matter  and  several 
dyeings  and  strippings  may  be  necessary  to  get  rid  of  this  in  order  to  show  the  pres- 
ence of  coal  tar  dyes. 

Chocolate  may  be  treated  similarly  but  the  following  procedure  is  preferable: 
Wash  20-200  grams  of  the  well  divided  sample  with  gasoline  on  a  filter  until  most  of 
the  fat  has  been  removed;  if  the  gasoline  is  colored,  reserve  for  the  examination  of 
oil-soluble  dyes  as  directed  under  3.  Remove  most  of  the  adherent  solvent  from  the 
residue  by  evaporation  or  pressure  between  layers  of  absorbent  paper  and  digest 
with  alcohol  as  directed  under  (d). 

Coal  tar  dyes  may  also  be  detected  in  chocolate  and  cocoa  products  by  mixing 
directly  with  3-4  times  their  weight  of  hot  water  and  immediately  boiling  the  magma 
with  wool,  as  directed  under  (a).  Because  of  the  presence  of  large  amounts  of  fatty 
and  protein  materials,  this  method  is  not  very  satisfactory. 

(f)  Cereal  products. — Proceed  as  directed  under  (d),  in  most  cases  working  with  a 
large  amount  of  the  sample,  200-500  grams,  and  a  relatively  smaller  amount  of  alcohol. 
Where  tests  are  to  be  made  only  for  the  acid  dyes,  the  extraction  with  neutral 
80%  alcohol  may  be  omitted  advantageously. 

3  OIL-SOLUBLE  DYES\ 

Prepare  an  alcoholic  solution  of  the  oil-soluble  dye  by  one  of  the  following  methods 
which  are  to  be  applied  to  the  oil  or  fat  obtained  by  extraction  with  ether  or  gasoline 
if  the  nature  of  the  substance  requires  it : 

(a)  Shake  the  oil  or  melted  fat  with  an  equal  volrnne  of  90%  alcohol.  The  alcohol 
after  separation  will  contain  Aniline  Yellow,  Butter  Yellow,  Aminoazotoluene  and 
Auramine,  if  present. 

(b)  Saponify  20-200  grams  of  the  oil  or  fat  with  alcoholic  potash  and,  after  re- 
moval of  most  of  the  alcohol  on  the  steam  bath,  extract  the  soap  with  ether  or  gaso- 
line. Most  of  the  common  dyes  are  removed  by  this  treatment,  though  the  digestion 
with  strong  alkali  may  cause  some  decomposition  and  make  the  extraction  rather 
troublesome. 


XIJ  COLORING   MATTERS   IN    FOODS  157 

(C)  Dilute  20-200  grams  of  the  oil  or  melted  fat  with  1-2  volumes  of  gasoline  and 
shake  out  successively  with  2-4%  potassium  or  sodium  hydroxid  solution,  12-15% 
hydrochloric  acid,  and  phosphoric-sulphuric  acid  mixture,  prepared  by  mixing 
85%  phosphoric  acid  with  about  10-20%  by  volume  of  concentrated  sulphuric  acid. 

The  dilute  alkali  extracts  Sudan  G  and  Annatto.  The  dilute  hydrochloric  acid 
extracts  Aniline  Yellow  (7),  Aminoazotoluene,  and  Butter  Yellow  {16),  the  first  2 
forming  orange-red,  the  latter  cherry-red  solutions  in  this  solvent.  Benzeneazo- 
beta-naphthylamin  and  homologues  also  come  in  this  group,  though  they  are  not 
extracted  very  readily  and  decompose  rapidly  on  standing  in  strongly  acid  solution. 
The  phosphoric  acid  mixture  is  necessary  for  the  extraction  of  Sudan  I  (11),  Sudan 
II  (49),  Sudan  III  (14^),  and  the  homologue  of  the  last,  Sudan  IV.  The  procedure 
is  not  very  suitable  in  the  presence  of  Auramine  but  this  dye  is  seldom  found  in  oils. 
Neutralize  the  alkaline  and  dilute  hydrochloric  acid  solutions;  dilute  the  phosphoric 
acid  mixture  and  partially  neutralize,  cooling  the  liquid  during  this  operation; 
and  extract  the  dyes  by  shaking  with  ether  or  gasoline. 

For  the  direct  dyeing  test  use  the  alcoholic  solution,  obtained  as  directed  in  (a). 
Evaporate  to  dryness  the  ether  or  gasoline  solutions,  obtained  as  directed  in  (b)  and 
(C),  and  dissolve  the  residue  in  10-20  cc.  of  strong  alcohol.  To  the  alcoholic  solution 
add  some  strands  of  white  silk  and  a  little  water  and  evaporate  on  the  steam  bath  until 
the  alcohol  has  been  removed  or  until  the  dye  is  taken  up  by  the  silk.  The  dyeing 
test  is  sometimes  unsatisfactory  and  in  all  cases  a  small  portion  of  the  alcoholic  solu- 
tion should  be  tested  by  treating  with  an  equal  volume  of  concentrated  hydrochloric 
acid  and  stannous  chlorid  solution.  The  common  oil-soluble  coal  tar  dyes  are  ren- 
dered more  red  or  blue  by  the  acid  and  are  decolorized  by  the  reducing  agent.  Most 
of  the  natural  coloring  matters  become  slightly  paler  with  the  acid  and  are  little 
changed  by  the  stannous  chlorid  solution. 

Separation  of  Coloring  Matters  in  Pure  Condition  by  Means  of 
Immiscible  Solvents''. 

4  preparation  of  sample. 

(a)  Water-soluble  colors. — Proceed  as  directed  under  2,  omitting  the  fixation  of 
the  color  on  wool,  and  obtain  an  aqueous  solution  as  free  as  practicable  from  sus- 
pended matter,  alcohol,  acids,  alkalies  and  salts. 

(b)  Water-insoluble  lakes. — If  the  sample  is  in  solid  form,  treat  the  well  divided 
material  with  sufficient  water  to  form  a  paste.  Liquids  require  no  preparation 
except  the  removal  of  alcohol  when  present. 

5  Mixtures  of  Orange  I,  Erythrosine,  Indigo  Carmine,  Amaranth, 

Tartrazine,  Naphthol  Yellow  S,  Ponceau  3R  and 
Light  Green  S  F  Yellowish. 

The  use  of  immiscible  solvents  for  the  separation  of  mixtures  of  coloring  matters 
usually  involves  a  systematic  fractionation  since  many  of  the  dyes  used  do  not  differ 
very  greatly  in  their  solubilities  in  the  various  solvents.  When  it  seems  probable 
that  only  the  8  coal  tar  dyes  permitted  under  the  Federal  Food  and  Drugs  Act^ 
are  present,  the  following  abridged  procedure  may  be  used  for  their  separation.  For 
this  procedure  the  concentration  of  the  dye  solution  should  lie  preferably  between 
0.01-0.05%.  The  solutions  obtained  in  the  examination  of  colored  food  products 
practically  never  require  further  dilution  but  with  commercial  food  colors  care  must 
be  taken  that  the  concentration  is  not  too  high.  Treat  the  sample,  prepared  as 
directed  in  4,  with  one  half  its  volume  of  concentrated  hydrochloric  acid  and  extract 
a  few  times  with  amyl  alcohol.     The  use  of  the  centrifuge  is  sometimes  necessary 


158  METHODS    OF   ANALYSIS  [Chap. 

to  separate  the  layers.  Designate  the  residual  aqueous  layer  as  A.  Combine  the 
amyl  alcohol  extracts  and  wash  with  4-5  portions  of  N/4  hydrochloric  acid  or  until 
this  solvent  extracts  very  little  color.  These  washings  will  contain  any  Indigo 
Carmine,  Amaranth  and  Tartrazine  present,  the  Indigo  Carmine  being  removed  in 
somewhat  larger  proportion  in  the  first  washings  than  the  other  2.  With  ordinary 
concentration  very  little  Ponceau  will  be  removed.  Designate  these  combined 
washings  as  B. 

6  ORANGE  I  AND  ERYTHROSINE. 

Measure,  if  necessary,  the  amyl  alcohol  extract,  under  5,  then  (1)  Dilute  with  an 
equal  volume  of  petroleum  ether  or  low  boiling  gasoline,  and  again  wash  several 
times  with  N/4  hydrochloric  acid  to  extract  Ponceau  3R  and  Naphthol  Yellow  S; 
or,  (2)  Without  dilution  with  gasoline,  wash  with  5%  salt  solution  until  these  2  dyes 
are  extracted.  Designate  these  washings  as  C.  The  Ponceau  and  Yellow  having 
been  removed,  the  amyl  alcohol,  containing  an  equal  volume  of  gasoline,  is  washed 
a  few  times  with  water  which  will  extract  Orange  I.  This  dye  having  been  removed, 
shake  the  solution,  although  the  latter  may  appear  almost  colorless,  with  very  dilute 
sodium  hydroxid  solution  to  remove  Erythrosine.  If  considerable  Orange  I  is  present, 
some  of  it  may  contaminate  the  washings  containing  the  Ponceau  3R  and  Naphthol 
Yellow  S,  especially  when  these  have  been  separated  by  means  of  N/4  hydrochloric 
acid  after  the  addition  of  gasoline. 

7  INDIGO  CARMINE,  AMARANTH  AND  TARTRAZINE. 

The  presence  of  2  or  all  3  of  these  dyes  is  usually  indicated  by  the  appearance 
of  the  N/4  hydrochloric  acid  washings,  B,  under  5.  Evaporate  the  combined  N/4 
hydrochloric  acid  washings  to  dryness  to  remove  the  excess  of  hydrochloric  acid  and 
dissolved  amyl  alcohol.  Dissolve  the  residue  in  water,  divide  the  solution  and  iden- 
tify the  constituent  colors  in  the  portions.  To  a  portion  of  the  slightly  acidified 
solution  add  a  few  decigrams  of  urea,  warm  and  add  1  or  2  drops  of  sodium  nitrite 
solution.  Indigo  Carmine  is  converted  into  the  pale  yellow  isatin  sulphonate  while 
the  other  dyes  are  but  little  affected.  The  isatin  compound  is  not  ordinarily  present 
in  sufficient  concentration  to  tint  the  solution  but  it  differs  from  Tartrazine  also  in 
being  much  less  readily  extracted  by  amyl  alcohol  from  strong  acid  solutions  (less 
than  one  half  from  4N  acid).  The  solution  now  contains  the  Amaranth  or  Tar- 
trazine, or  both,  practically  unaffected.  Amaranth  is  much  more  quickly  attacked 
by  most  reducing  agents  than  Tartrazine.  Treat  the  solution,  which  should  be  neu- 
tral or  faintly  acid  (in  the  presence  of  sodium  carbonate  the  reduction  of  the  tar- 
trazine takes  place  still  more  slowly),  at  room  temperature  with  a  dilute  solution  of 
sodium  hyposulphite  (Na2S204),  adding  the  latter  very  carefully,  drop  by  drop,  and 
allowing  sufficient  time  after  the  addition  of  each  drop  for  the  reduction  to  take 
place.  When  the  color  shows  that  the  Amaranth  has  been  destroyed  completely, 
shake  the  mixture  at  once  with  air  to  oxidize  the  slight  excess  of  hyposulphite  before 
it  can  react  further  on  the  Tartrazine. 

To  separate  the  Indigo  Carmine  heat  to  boiling  another  portion  of  the  solution, 
which  should  be  neutral  or  faintly  acid,  and  add  dilute  sodium  hyposulphite  solution, 
drop  by  drop,  until  all  the  dyes  are  reduced.  On  shaking  with  air  the  Indigo  Carmine 
is  quickly  re-formed. 

8  NAPHTHOL  YELLOW  S  AND  PONCEAU  3R. 

Treat  the  N/4  acid  solution  or  the  salt  solution,  C,  under  6,  as  the  case  may  be, 
containing  the  Ponceau  and  Naphthol  Yellow  S,  with  enough  hydrochloric  acid  to 
make  it  about  2N  and  shake  out  a  few  times  with  washed  ethyl  acetate*.     Remove 


XI]  COLORING   MATTERS   IN   FOODS  159 

the  Yellow  from  the  combined  ethyl  acetate  extracts  by  shaking  with  water.  Naph- 
thol  Yellow  S  is  almost  colorless  in  strongly  acid  solutions,  and  its  absence  in  wash- 
ings, etc.,  must  never  be  assumed  until  these  have  been  made  alkaline.  Finally 
separate  the  Ponceau  3R  from  the  acid  solution  by  shaking  with  amyl  alcohol,  and 
then  wash  out  the  dye  from  this  extract  with  a  few  small  portions  of  water.  If, 
in  the  case  of  mixtures  containing  Orange  I,  the  washings  of  the  ethyl  acetate,  which 
should  contain  only  Naphthol  Yellow  S,  become  more  red  upon  the  addition  of  al- 
kalies, combine,  then  (1)  Make  N/4  with  hydrochloric  acid  and  remove  the  contami- 
nating Orange  by  shaking  with  amyl  alcohol-gasoline  mixture  (1  to  1);  or,  (2)  Treat 
the  combined  washings  mth  one  fifth  their  volume  of  concentrated  hydrochloric 
acid,  extract  the  dyes  by  shaking  once  with  amyl  alcohol,  and  remove  the  Yellow 
by  washing  with  several  portions  of  5%  salt  solution. 

9  LIGHT   GREEN  S  F  YELLOWISH. 

The  original  mixture,  A,  under  5,  from  which  the  above  mentioned  7  colors  have 
been  removed  by  adding  acid  and  shaking  out  with  amyl  alcohol,  may  still  contain 
Light  Green  S  F  Yellowish,  which  will  be  colorless  or  nearly  so  in  the  acid  solution. 
To  separate  this  dye  treat  the  mixture  with  strong  ammonia  or  potassium  hydrox- 
id  solution  until  slightly  alkaline,  and  neutralize  with  acetic  acid.  Any  Green 
present  will  now  be  apparent  by  the  color  of  the  mixture.  Extract  the  color  by 
shaking  with  a  few  small  portions  of  dichlorhydrin.  Wash  the  dichlorhydrin  extract 
with  a  little  water,  then  dilute  with  several  volumes  of  benzene  or  carbon  tetra- 
chlorid,  and  remove  the  dye  by  shaking  with  water. 

When  coal  tar  dyes  other  than  the  8  mentioned  above  are  present,  the  solutions 
obtained  in  this  procedure  will  be  found  to  contain  a  coloring  matter  which  does  not 
correspond  exactly  in  properties  to  one  of  the  dyes  named  above.  When  coal  tar 
dyes  other  than  these  8  are  present,  reference  should  be  made  to  the  larger  works'. 

Coal  Tar  Dyes  in  General. 

10  basic  dyes. 

Most  basic  dyes  may  be  separated  from  mixtures  by  making  alkaline  with  sodium 
hydroxid  and  shaking  with  ether'".  Use  the  sample,  prepared  as  in  4,  for  this  pur- 
pose. Separate  the  ether  layer,  which  may  or  may  not  be  colored,  and  shake  with 
2-5%  acetic  acid,  which  will  take  up  any  dye  present,  forming  a  colored  solution. 
Although  the  common  basic  colors  undergo  some  alteration  by  this  treatment", 
it  may  be  used  for  the  qualitative  detection  and  separation  of  Methyl  Violet  B  {4-51), 
Magenta  {U8),  Bismarck  Brown  (197),  Malachite  Green  (427),  and  Rhodamine  B 
(504).  With  care  Auramine  (425)  may  also  be  separated  in  this  way  though  it  is 
quickly  decomposed  on  standing  in  alkaline  solution. 

11  ACID   DYES. 

The  following  short  procedure  is  often  convenient  for  the  examination  of  mixtures 
of  acid  dyes:  Make  the  sample,  prepared  as  in  4,  the  color  concentration  of  which 
does  not  vary  greatly  from  0.01-0.05%,  strongly  acid  by  adding  one  half  its  volume 
of  concentrated  hydrochloric  acid  and  shake  with  amyl  alcohol.  Separate  the 
amyl  alcohol  solution  and  wash  by  shaking  with  successive  portions  of  one  half  its 
volume  of  water,  reserving  the  portions  in  separate  test  tubes  or  beakers.  Because 
of  the  acid  dissolved  in  the  amyl  alcohol  these  washings  will  show  a  regular  decrease 
in  acidity  and  the  coloring  matters  will  appear  in  maximum  amount  in  the  different 
fractions  according  to  their  respective  solubilities.  Ponceau  6R  (108)  is  washed 
out  chiefly  while  the  acidity  is  still  high,  N/1  or  above.     Amaranth  (107),  Brilliant 


160  METHODS    OF   ANALYSIS  [Chap. 

Scarlet  (106)  and  Tartrazinc  (94)  appear  when  the  washings  have  an  acidity  between 
N/1  and  N/4;  Orange  G  (14)  and  Sohible  Blue  (480)  between  N/2  and  N/16;  Palatine 
Scarlet  (53),  Ponceau  2R  (55)  and  3R  (56),  Naphthol  Yellow  S  (4),  Cochineal  (706), 
Crystal  Ponceau  (64)  and  Azorubine  A  (103)  between  N/IG  and  N/256.  When  the  acid 
is  practically  all  removed,  Orange  I  (85),  Orange  II  (86)  and  Croceine  Orange  (13) 
begin  to  wash  out,  and  less  readily.  Orange  IV  (88)  and  Metanil  Yellow  (95).  Finally 
the  unsulphonated  coloring  matters,  such  as  Erythrosine  G  (516),  Erythrosine  (517) 
and  the  Rose  Bengals  (520  and  523)  are  removed  very  slowly  by  water  or  not  at  all 
when  all  traces  of  acid  have  been  removed.  Acid  Yellow  (8)  and  Brilliant  Yellow 
S  (89)  are  not  very  uniform  in  composition.  They  are  partially  taken  up  by  amyl 
alcohol  from  acid  solution  and  appear  chiefly  in  the  first  washings.  Indigo  Carmine 
(692)   behaves  somewhat  similarly. 

Identification  of  the  Coal  Tar  Dyesi^. 

1 2  general. 

The  most  widely  used  tests  for  the  identification  of  coal  tar  dyes  refer  to  the 
changes  produced  with  acids  and  alkalies.  Other  tests,  based  upon  the  behavior 
with  reducing  agents,  followed  perhaps  by  treatment  with  oxidants  or  by  separation 
and  identification  of  the  reduction  products^',  and  tests  based  upon  oxidation  of  the 
dye  and  treatment  of  the  oxidation  products^^  are  generally  applicable.  Spectro- 
scopic methods  are  also  used^^. 

13  COLOR  CHANGES  PRODUCED  WITH  ACIDS  AND  ALKALIES. 

Transfer  the  separated  coloring  matter  to  wool  (or  silk  in  the  case  of  oil-soluble 
dyes)  by  boiling  as  directed  in  2  (a)  or  3.  Care  should  be  taken  that  the  final  dyeing 
is  made  in  a  solution  fairly  free  from  foreign  matter  such  as  sugar  or  aromatic  sub- 
stances, which,  adhering  to  the  fiber,  may  modify  the  reaction.  In  most  cases  the 
amount  of  color  available  is  small  and  should  not  be  dyed  on  too  large  a  piece  of  wool 
(or  silk).  Rinse  thoroughly  the  dyed  fibre  in  rmining  water,  dry,  cut  into  small  pieces 
and  place  separately  in  the  depressions  of  a  white  porcelain  spot  plate.  Moisten  the 
pieces  with  the  respective  reagents  employed.  (For  many  coloring  matters  the 
hue  upon  treatment  with  acids  or  alkalies  varies  markedly  with  the  concentration 
of  the  reagents  and  amount  of  dye  present;  therefore  the  unknown  dye  should  be 
compared  with  dyeings  of  known  colors  of  approximately  the  same  dye  concentration 
as  shown  by  this  appearance.) 

The  table  under  14  shows  the  color  changes  produced  by  concentrated  hydro- 
chloric and  sulphuric  acids,  10%  sodium  hydroxid  and  12%  ammonium  hydroxid 
solutions  on  wool  dyed  with  0.1-0.5%  of  the  respective  coloring  matters.  Included 
also  are  the  reactions  of  the  oil-soluble  colors  but  these  refer  to  dyeings  on  silk. 
The  dyes  are  arranged  approximately  according  to  hue.  Brown  is  classed  with 
orange,  black  (gray)  with  violet. 


XI] 


COLORING   MATTERS    IN   FOODS 


161 


14 


Table  14. 
Color  reactions  produced  on  dyed  fibers  by  various  reagents. 


COLORING  MATTER 

HYDROCHLORIC 
ACID 

SULPHURIC  ACID 

SODIUM  HYDROXID 

AMMONIUM 
HVOROXID 

Rhodamine  B 

501, 

Orange 

Yellow 

Bluer 

Bluer 

Rose  Bengal 

523 

Almost 

decolorized 

Orange 

No  change 

No  change 

Archil 

710 

Red 

Dull  brown 

Violet 

Violet 

Magenta 

US 

Yellowish 
brown 

Dull  brown 

Decolorized 

Paler 

Acid  Magenta 

m 

Almost 

decolorized 

Yellow 

Decolorized 

Decolorized 

Piilatine  Red 

62 

Darker 

Violet 

Dull  brown 

Little  change 

Bordeaux  B 

65 

Violet 

Blue 

Brown 

Little  change 

Amaranth 

107 

Slightly 

Violet  to 

Dull     brown- 

Little change 

darker 

brownish 

ish 

Azorubine  A 

ion 

Little  change 

Violet 

Red 

Rod 

Erythrosine 

517 

Orange-yellow 

Orange-yellow 

No  change 

No  change 

Ponceau  6RB 

169 

Blue 

Blue 

Dull    violet- 
red 
Brown 

Little  change 

Ponceau  6R 

108 

Violet-red 

Violet 

Orange-red 

Crystal 

64 

Violet-red 

Violet 

Dull  brown 

Little  change 

Ponceau 

Ponceau  3R 

56 

Little  change 

Little  change 

Dull  orange 

Little  change 

Sudan  III* 

US 

Violet,     then 
brown 

Green 

Violet-red 

Little  change 

Safranine 

584 

Greenish  blue 

Green 

Red 

Red 

Brilliant 

106 

Red 

Violet-red 

Yellowish 

Orange-red 

Scarlet 

brown 

Ponceau  2R 

55 

Little  change 

Little  change 

Brownish 
j'Cllow 

No  change 

Palatine 

53 

Darker 

Violet-red 

Brownish 

No  change 

Scarlet 

yellow 

Ervthrosine  G 

516 

Yellow-orange 

Yellow-orange 

No  change 

No  change 

Sudan  11* 

49 

Red 

Violet-red 

Little  change 

No  change 

Sudan  1* 

11 

Orange-red 

Red 

Redder 

No  change 

Cochineal 

706 

Little  change 

Little  change 

Violet-red 

Violet-red 

Bismarck 

197 

Redder, 

Browner 

Yellower 

Yellower 

Brown 

darker 

Bismarck 

201 

Redder, 

Browner 

Yellower 

Yellower 

Brown  R 

darker 

Orange  I 

85 

Violet 

Violet 

Red,  dark 

Red,  dark 

Orange  11 

86 

Red 

Red 

Dull  red 

No  change 

Croccine 

13 

Orange-red 

Orange 

Slightly 

No  change 

Orange 

darker 

Orange  G 

14 

Little  change 

Orange 

Dull,  brown- 
ish red 

No  change 

Orthotoluene- 

Red 

Violet 

Little  change 

No  change 

azo-beta- 

naphthyl- 

amine* 

Sudan  G* 

10 

Orange-yellow 

Brownish 
yellow 

Orange-yellow 

No  change 

Butter  Yellow* 

16 

Violet-red 

Orange-yellow 

No  change 

No  change 

Aniline  Yellow* 

7 

Brownish  red 

Orange-yellow 

Little  change 

No  change 

Aminoazo- 

Dull  orange 

Orange-yellow 

Little  change 

No  change 

ortho-tolu- 

ene* 

162 


METHODS    OF   ANALYSIS 


[Chap. 


14 

Table  14.— Continue 

d. 

COLORING  MATTER 

HYDROCHLORIC 
ACID 

SULPHURIC  ACID 

SODIUM  HYDROXID 

AMMONIUM 
HYDROXID 

Fluoresceine 

510 

Little  change 

Little  change 

Green     flu- 
orescent 

Green    flu- 
orescent 

Meianil  Yellow 

95 

Violet-red 

Violet 

No  change 

No  change 

Azoflavine 

92 

Violet-red 

Violet-red 

Dull  brown 

Little  change 

Acid  Yellow 

8 

Red 

Orange 

Little  change 

No  change 

Brilliant 

89 

Violet-red 

Violet-red 

Little  change 

Little  change 

Yellow  S 

Tartrazine 

94 

Slightly 
darker 

Slightly 
darker 

Little  change 

Little  change 

Naphthol 

4 

Almost 

Very    pale, 

No  change 

No  change 

Yellow  S 

decolorized 

dull  brown 

Auramine 

425 

Decolorized 

Almost 
decolorized 

Decolorized 

Paler 

Turmeric 

707 

Red 

Reddish 
brown 

Orange 

Orange 

Quinoline 

667 

Slightly 

Brownish 

Slightly 

Little  change 

Yellow 

darker 

yellow 

paler 

Naphthol 

398 

Yellowish 

Brownish 

No  change 

No  change 

Green  B 

yellow 

Guinea  Green 

433 

Pale    orange- 

Pale,  dull 

Decolorized 

Decolorized 

B 

yellow 

yellow 

Light  Green  S  F 

435 

Pale    orange- 

Pale,  dull 

Decolorized 

Decolorized 

Yellowish 

yellow 

vellow 

Night  Green  2B 

438 

Pale   orange- 
yellow 

Pale,  dull 
yellow 

Decolorized 

Paler 

Malachite 

427 

Almost 

Almost 

Decolorized 

Decolorized 

Green 

decolorized 

decolorized 

Erioglaucine  A 

436 

Yellow 

Pale,  dull 
yellow    or 
brown 

Slightly 
darker 

Little  change 

Patent  Blue  A 

442 

Pale    orange- 
yellow 

Pale    or    dull 
brown 

Little  change 

Little  change 

Soluble  Blu« 

480 

Paler 

Brown 

Pale  reddish 

Almost  decol- 
orized 

Indigo  Carmine 

692 

Slightly 

Slightly 

Greenish  yel- 

Greenish blue 

darker 

darker 

low 

Formyl  Violet 

468 

Pale    orange- 
vellow 

Pale,  dull 
orange 

Decolorized 

Decolorized 

Methyl  Violet  B 

451 

Yellowish 

Yellowish 

Decolorized 

Almost  decol- 
orized 

Nigrosine,  sol- 

602 

Dull  bluish 

Dull  greenish 

Brownish  red, 

Pale  reddish 

uble 

paler 

15         SPECIAL  TESTS  FOR  COAL  TAR  DYES  PERMITTED'  UNDER  THE   FEDERAL 
FOOD  AND    DRUGS  ACT. 

The  dyes,  given  in  5,  are  sufficiently  characterized  in  most  cases  by  the  solubilities 
shown  in  their  separation  and  by  the  color  changes  given  by  acids  and  alkalies  on 
the  dyed  fiber.  This  is  especially  true  with  Amaranth,  Tartrazine,  and  Orange  I. 
By  treatment  with  reducing  agents  such  as  stannous  chlorid,  titanous  chlorid,  zinc 
dust  or  sodium  hyposulphite  in  acid  solution,  Indigo  Carmine,  Amaranth,  Tartra- 
zine, Ponceau  3R  and  Orange  I  are  decolorized.  With  Indigo  Carmine  the  color 
returns  on  shaking  with  air,  most  readily  on  warming,  or  on  the  addition  of  oxidiz- 
ing agents  such  as  ferric  chlorid  or  potassium  persulphate.  Excess  of  the  reducing 
agents  must  of  course  be  avoided.  With  the  last  4  named  dyes  the  color  is  not  re- 
stored.    Dilute  solutions  of  Light  Green  S  F  Yellowish,  Naphthol  Yellow  S  and 


XI]  COLORING   MATTERS   IN   FOODS  163 

Erythrosine  become  paler  or  colorless  with  acids  so  that  the  effects  of  acid  reducing 
agents  are  not  so  readily  apparent.  Neutral  solutions  of  Naphthol  Yellow  S  are 
decolorized  by  sodium  hyposulphite  and  other  reducing  agents,  the  color  not  return- 
ing with  air  or  oxidants.  An  evanescent  deepening  of  the  shade  may  take  place 
immediately  upon  the  addition  of  the  hyposulphite.  Erythrosine  and  Light  Green 
S  F  Yellowish  become  paler  with  sodium  hyposulphite,  the  color  being  partially 
restored  upon  the  addition  of  potassium  persulphate. 

In  hot  solutions  containing  an  excess  of  sodium  tartrate  the  dyes  named 
are  readily  decolorized  by  titanium  trichlorid".  In  the  case  of  Indigo  Carmine  if 
the  reducing  agent  has  been  added  carefully  and  an  excess  avoided,  the  blue  color 
readily  returns  on  shaking  with  air.  With  Erythrosine  and  Light  Green  S  F  Yel- 
lowish the  color  is  scarcely  restored  by  air  but  on  cooling  and  adding  potassium 
persulphate  returns  imperfectly.  The  reduction  products  of  the  other  dyes  do 
not  give  colored  solutions  again  on  oxidation  disregarding  a  slight  yellowish  or 
brownish  tint  that  may  sometimes  appear. 

Indigo  Carmine  is  extracted  in  small  proportions  from  slightly  acid  solutions  by 
shaking  with  dichlorhydrin.  Most  of  the  other  common  bluish  dyes  are  triphenyl- 
methane  derivatives  and  are  relatively  more  soluble  in  this  liquid  than  in  the  aque- 
ous layer.  A  small  portion  (1  cc.)  of  the  solution  obtained  in  the  separation,  5, 
may  be  used  directly. 

Ponceau  SR  gives  in  neutral  or  faintly  acid  solutions  a  bluish  red,  flocculent  pre- 
cipitate with  barium  chlorid  or  acetate,  practically  all  of  the  dye  being  removed  from 
solution.  Some  of  the  solution  obtained  in  the  separation,  5,  may  be  used  in  this 
test,  first  neutralizing  the  free  hydrochloric  acid  with  sodium  acetate;  or  better,  it 
may  be  evaporated  to  dryness  on  the  steam  bath  to  remove  the  acid  and  the  residue 
taken  up  with  a  little  water.  The  solution  should  contain  0.005%  or  more  of  the 
dye. 

Naphthol  Yellotv  S,  in  solutions  containing  an  excess  of  ammonia  or  sodium  car- 
bonate, becomes  intensely  rose-red  on  the  addition  of  sodium  hyposulphite,  the  color 
gradually  fading  again  as  complete  reduction  takes  place. 

Erythrosine  differs  from  most  of  the  common  dyes  by  containing  iodin.  To  test 
for  this,  acidify  the  solution  with  sulphuric  acid,  shake  with  ether,  separate  the 
ether  solution  of  the  color  and  evaporate  to  dryness  in  a  platinum  dish  after  the 
addition  of  a  few  drops  of  sodium  carbonate  solution  or  sufficient  to  form  the  deep 
red  sodium  salt.  Hold  the  dish  containing  the  residue  in  the  Bunsen  flame  until 
organic  matter  is  destroyed,  take  up  the  residue  with  water,  acidify  with  sulphuric 
acid  and  test  for  iodin  in  one  of  the  usual  ways,  such  as  with  chlorin  water  and  carbon 
disulphid  or  tetrachlorid,  or  with  starch  paste  and  an  oxidizing  agent.  It  is  useless 
to  test  for  iodin  with  very  small  amounts  of  dye  but  in  most  cases  sufficient  coloring 
matter  can  be  separated  from  the  food  product  to  give  satisfactory  results. 

16  Natural  Coloring  Matters. 

The  natural  coloring  matters  as  a  class  show  much  less  tendency  to  dye  animal 
fiber  than  do  the  common  synthetic  colors.  In  many  cases  the  crude  products  used 
contain  a  number  of  colored  substances  and  a  complete  separation  can  scarcelj'  be 
attempted.  Most  of  the  natural  coloring  matters,  in  dilute  solution,  are  sensitive 
to  alkalies,  some  to  acids,  hence  such  reagents  must  be  used  with  care. 


164  METHODS    OF   ANALYSIS  [Chap. 

SEPARATION   OF  NATURAL  COLORING  MATTERS. 

17  Exlraclion  with  Ether  from  Neutral  Solutions. 

From  neutral  solutions  ether  extracts  Carotin,  Xanthophyll  (the  pigment  found  in 
leaves,  fats  and  oils,  egg  yolk,  carrots,  etc.),  the  coloring  matter  of  tomatoes  and 
paprika  and  green  Chlorophyll.  The  coloring  matter  remains  in  the  ether  solution 
on  shaking  with  dilute  sodium  hydroxid  solution  or  dilute  hydrochloric  acid,  no 
apparent  change  taking  place  although  chemically  the  substances  may  be  altered 
more  or  less  by  this  treatment. 

18  Extraction  with  Ether  from  Acid  Solutions, 

From  slightly  acid  solutions  ether  extracts  very  readily  and  completely  the 
coloring  matter  of  Alkanet,  Annatto,  Turmeric,  and  the  red  dyewoods,  Sandalwood, 
Camwood  and  Barwood.  It  extracts  in  large  proportion  the  flavone  coloring  matters 
of  Fustic,  Persian  Berries  (after  hydrolysis),  and  Quercitron  as  well  as  the  coloring 
matter  of  Brazilwood  and  the  green  derivatives  formed  from  Chlorophyll  by  alkaline 
treatment.  It  extracts  in  relatively  small  amount  the  coloring  matters  of  Logwood, 
Archil,  Saffron  and  Cochineal.  The  coloring  matters  of  this  group  are  readily  re- 
moved from  ether  by  shaking  with  alkaline  solutions  but  in  most  cases  rapidly 
undergo   chemical   change. 

19  Extraction  with  Amijl  Alcohol  from  Acid  Solutions. 

From  slightly  acid  solutions  amyl  alcohol  extracts  largely  the  coloring  matters  of 
Logwood,  Archil,  Saffron  and  Cochineal.  [From  ammoniacal  Cochineal  (Carmine) 
the  ordinary  coloring  matter  is  readily  re-formed  upon  standing  with  hydrochloric 
acid.]  Amyl  alcohol  extracts  in  relatively  small  proportions  Caramel  and  the  Antho- 
cyans  constituting  the  red  coloring  matter  of  the  most  common  fruits. 

IDENTIFICATION   OF   NATURAL  COLORING  MATTERS. 

20  REAGENTS. 

(a)  Hydrochloric  acid. — Sp.  gr.  L20. 

(b)  10%  sodium  or  potassium  hydroxid  solution. 

(C)  Sodium  hyposulphite  solution. — A  freshly  prepared  5%  solution  of  "Blankite", 
sodium  hyposulphite  (Na2S204). 

(d)  0.6%  ferric  chlorid  solution.— Freshly  prepared  but  may  be  made  by  diluting  a 
10%  stock  solution. 

(e)  10%o  potassium  or  ammonium  alum,  solution. 

(f )  5%  uranium  or  sodium  uranium  acetate  solution 

(g)  Sulphuric  acid. — Sp.  gr.  L84. 

21  PROCEDURE. 

Relatively  few  good  tests  are  known  for  the  common  natural  colors.  Some  of 
their  most  useful  analytical  properties'^  are  tabulated  in  22.  In  general  these  tests 
should  be  applied  to  the  somewhat  purified  solutions  of  the  coloring  matter  obtained 
as  indicated  in  17,  18  or  19. 

Evaporate  ether  solutions  to  dryness,  warm  the  residue  with  a  little  alcohol  and 
dilute  the  alcoholic  solution  with  water.     Apply  the  reagents  as  stated  below: 


XI]  COLORING   MATTERS   IN   FOODS  165 

Hydrochloric  acid. — Add  concentrated  acid  (sp.  gr.  1.20)  to  the  solution,  first 
1  or  2  drops,  then  a  large  excess,  equal  to  3-4  times  the  volume  of  the  solution. 

Sodium  hydroxid  {-potassium  hydroxid). — Make  the  solution  slightly  alkaline  by 
adding  a  drop  of  the  10%  sodium  hydroxid  solution.  A  10%  solution  of  potassium 
hydroxid  in  methyl  alcohol  must  be  used  for  the  "brown  phase  reaction"  for  chloro- 
phyll, described  in  23,  and  may  also  be  employed  for  the  other  tests. 

Sodium  hyposulphite. — Add  the  sodium  hyposulphite  solution  drop  by  drop. 

Ferric  chlorid. — Add  a  small  amount  of  the  0.5%  ferric  chlorid  solution  to  the 
solution  to  be  tested.  The  reagent  must  be  added  very  carefully,  a  small  drop  at  a 
time,  as  the  colorations  are  not  obtained  in  all  ca.ses  when  an  excess  is  used. 

Alu7n. — Add  to  the  test  solution  one  fifth  its  volume  of  the  10%  potassium  or 
ammonium  alum  solution. 

Uranium  acetate. — Add  the  5%  uranium  acetate  solution  drop  by  drop  to  the  solu- 
tion to  be  tested. 

Concentrated  sulphuric  acid  on  the  dry  color. — Evaporate  a  small  amount  of  the 
solution  or  of  the  coloring  matter  in  a  porcelain  dish.  Cool  thoroughly  and  treat 
the  dry  residue  with  1  or  2  drops  of  cold,  concentrated  sulphuric  acid.  The  color- 
ations are  in  some  cases  extremely  fugitive  and  may  be  observed  only  the  instant 
the  acid  wets  the  residue. 

The  properties  of  pure  preparations  of  the  various  natural  coloring  matters  are 
described,  for  the  most  part,  by  Rupe*^.  Properties  of  the  Chlorophylls  and 
Carotinoids  are  given  by  Willstiitter  and  StolP^.  Those  of  the  coloring  matters  of 
the  Corn  Flower,  Rose,  Pelargona  Flower,  Larkspur,  Cranberry,  Whortleberry  and 
Purple  Grape  are  described  by  Willstattcr^". 


166 


METHODS    OF   ANALYSIS 


[Chap. 


PI 

cl 

03   O 
-dZ3 

1^ 

§    5 

i  3 

>    > 

0 

o 

'3 
!> 

:                              lg 

"1 

s 

i 

e 
S 

s 

o 

E 
.J 

g 

s 

0 

Rose-red 
(change 
rather 
slow) 

Rose-red 
(change 
rather 
slow) 

h 

Dark  shades 
of  violet, 
brown    or 
black    (the 
first  hue  of- 
ten   evanes- 
cent) 

Dark  shades  of 
violet,  brown 
or  black  (the 
first  hue  of- 
ten   evanes- 
cent) 

S 
s 

Almost   decol- 
orized, color 
returning 
imperfectly 
by    reoxida- 
tion 

Anthrocyani- 
dins  derived 
by  hydroly- 
sis,    almost 
completely 
decolorized 

Decolorized, 
color  return- 
ing   when 
shaken  with 
air.    Reac- 
tion   more 
easily   seen 
in    alkaline 
solution 

i 
1 

i 

Violet     to 
violet-blue 

Violet-red 

Change   to 
green,  dull 
blue    or 
slate    col- 
or, usually 
very 
quickly, 
becoming 
browner  by 
oxidation 

Deep  blue 

Blue 

g 

a 

Deep  red  with 
excess    of 
acid 

Deep  red  with 
excess   of 
acid 

o 

K 

S 
O 

i          1 
1          I 

(Brazilwood, 
Sandalwood, 
Camwood  and 
Barwood) 

Anthocyans  of 

red  fruit  col- 
ors 

Alkanet 

13 
< 

I 

XIJ 


COLORING   MATTERS   IN   FOODS 


167 


S 

Red 

Yellow 
to  orange 

Blue 

Blue,  reaction 

3 

Cl'O 

'Ih 

o 

Somewhat 
browner 

Orange  colora- 
tions 

Not  affected 

Little 
change 

More  strong- 
ly yellow; 
Fustic,  de- 
veloping a 
green    flu- 
orescence 

Little 
change 

Slightly  darker 

No  marked 

change 

Perhaps 

somewhat 

browner 
No  marked 

change. 

Perhaps 

somewhat 

browner 

Olive-green  or 
black  colora- 
tions 

No  marked 
change. 
Perhaps 
somewhat 
browner 
.    

1 
1 

No  marked 

change 
Little  affected 

Little  affected 

Little  affected 

Little  affected 
Little  affected 

i 
1 

> 

Orange-brown 

Bright-yellow 

Remains 
yellow 

Little  or  no 
change 

"Brown 
phase    re- 
action", 23 

Little 
change 
or  slightly 
deeper 
brown 

Little    or   no 

change 
Remains 

orange. 

Little 

change 

Orange^red  or 
carmine-red 
on    addition 
of       several 
volumes    o  f 
concentrated 
acid 

Becomes    in- 
tensely  yel- 
low with  2-4 
volumes    of 
concentrated 
acid 

Little    or    no 
change 

Little  change. 

Perhaps 

slightly 

paler 
More  brownish 

Little    or    no 
change 

^ 
C 

3        " 
J       c 
3        c 

Turmeric  (solu- 
tion in  ether 
or  alcohol 
characterized 
by  pure  yel- 
low color  and 
light  green 
fluorescence) 

Flavone  colors 
of  Fustic,  Per- 
sian Berries, 
Quercitron, 
etc. 

Saffron 

1  i 

1   c 

^  1 

1    2 

C       oJ 

o 

168  METHODS    OF   ANALYSIS  [Chap. 

Special  Tests  for  Natural  Coloring  Matters. 

23  chlorophyll. 

The  "brown  phase  reaction"-'  may  be  useful  for  the  characterization  of  Chloro- 
phyll, when  this  has  not  been  previously  treated  with  alkalies.  Treat  the  green 
ether  or  petroleum  ether  solution  of  the  coloring  matter  with  a  small  amount  of 
10%  solution  of  potassium  hydroxid  in  methyl  alcohol.  The  color  becomes  brown, 
returning  to  green  in  a  few  minutes. 

annatto. 

24  Leach    Test"-. 

Pour  on  a  moistened  filter  an  alkaline  solution  of  the  color  obtiined  by  shaking  out 
the  oil  or  melted  and  filtered  fat  with  warm,  dilute  sodium  hydroxid  solution.  If 
Annatto  is  present,  the  filter  paper  will  absorb  the  color  so  that,  when  washed  with 
a  gentle  stream  of  water,  it  will  remain  dyed  a  straw  color.  Dry  the  filter  and  add  a 
drop  of  stannous  chlorid  solution.  If  the  color  turns  pink  the  presence  of  Annatto 
is  confirmed. 

25  turmeric. 

Carry  out  the  highly  characteristic  reaction  of  Curcumine  (Turmeric)  with  boric 
acid  as  follows:  Treat  the  aqueous  or  dilute  alcoholic  solution  of  the  color  with 
hydrochloric  acid  until  the  shade  just  begins  to  appear  slightly  orange.  Divide 
the  mixture  into  2  parts  and  add  some  boric  acid  powder  or  crystals  to  1  portion. 
A  marked  reddening  will  be  quickly  apparent,  best  seen  by  comparison  with  the 
portion  to  which  the  boric  acid  has  not  been  added.  The  test  may  also  be  made  by 
dipping  a  piece  of  filter  paper  in  the  alcoholic  solution  of  the  coloring  matter,  drying 
at  100°C.,  then  moistening  with  a  weak  solution  of  boric  acid  to  which  a  few  drops 
of  hydrochloric  acid  have  been  added.  On  drying  again  a  cherry-red  color  will  be 
developed. 

26  COCHINEAL. 

When  the  presence  of  Cochineal  is  suspected,  acidify  the  mixture  with  one  third 
its  volume  of  concentrated  hydrochloric  acid  and  shake  with  amyl  alcohol.  Wash 
the  amyl  alcohol  solution  of  the  coloring  matter  2-4:  times  with  equal  volumes  of 
water  to  remove  hydrochloric  acid,  etc.  Dilute  the  amyl  alcohol  with  1-2  volumes  of 
gasoline  and  shake  with  a  few  small  portions  of  water  to  remove  the  color.  Sepa- 
rate the  solution  into  2  portions.  To  the  first  add,  drop  by  drop,  5%  uranium  ace- 
tate solution,  shaking  thoroughly  after  each  addition.  In  the  presence  of  cochineal 
a  characteristic  emerald-green  color  is  produced-^  The  green  coloration  with 
uranium  salts  is  not  developed  in  the  presence  of  much  free  acid.  Therefore  add  a 
little  sodium  acetate  before  making  this  test  or  a  correspondingly  large  amount  of 
uranium  acetate  must  be  added.  To  the  second  portion  add  a  drop  or  so  of  ammon- 
ium hydroxid,  and,  in  the  presence  of  Cochineal,  a  violet  coloration  results.  This, 
however,  is  not  so  sensitive  to  small  amounts  as  the  first  test  and  many  fruit  colors 
give  tests  hardly  to  be  distinguished. 

As  cochineal  lakes  very  often  contain  tin,  further  examination  for  this  metal 
should  always  be  made  when  water-insoluble  cochineal  compounds  appear  to  be 
present. 


XI]  COLORING   MATTERS   IN   FOODS  169 

BIBLIOGRAPHY. 

'  Schultz.  Farbstofftabellon.  5th  German  ed.,  1911-14. 

2Abs.  Z.  anal.  Chem.,  1885,  24:  625;  1889,  28:  G39;  Conn.  Agr.  Exp.  Sta.  Rept., 
1899,  fll),  p.  130. 

3  J.Am.  Chem.  Soc,  1905,  27:  25. 

4  Abs.  Z.  anal.  Chem.,  1896,  35:  397. 

5U.  S.  Bur.  Chem.  Bull.  65,  p.  152;  Ann.  fals.,  1910,  3:  293;  U.  S.  Bur.  Chem. 
Circs.  25  and  63;  Abs.  Chem.  Zentr.,  1898,  (2),  943. 

^  U.  S.  Bur.  Chem.  Circs.  25  and  63;  Allen.  Commercial  Organic  Analysis.  4th 
ed.,  1909-14,  5;  Leach.  Food  Inspection  and  Analysis.  3rd  ed.,  1913;  Girard  and 
Dupre.  Analyse  des Malieres  Alimentaires  et  Recherches  de  leur  Falsification.  1894; 
J.  pharm.  chim.,  6th  ser.,  1901,  13:  175;  U.  S.  Bur.  Animal  Industry  Circ.  180. 

'  U.  S.  Dept.  Agr.,  F.  I.  Ds.  76  and  164. 

8  U.  S.  Bur.  Chem.  Bull.  162,  p.  57. 

^  Heumann.  Die  Anilinfarben  und  ihre  Fabrikation.  1888-1906;  Green.  Sys- 
tematic Survey  of  the  Organic  Colouring  Matters.  2nd  ed.,  rev.,  1904,  based  on  the 
German  of  Schultz  and  Julius;  Schultz.  Farbstofftabellen.  5th  German  ed.,  1911- 
14;  Allen.  Commercial  Organic  Analysis.  4th  ed.,  1909-14,  5;  MuUiken.  Identifi- 
cation of  Pure  Organic  Compounds.     1910,  3. 

10  Abs.  Z.  anal.  Chem.,  1887,  26:  100;  1888,  27:  232. 

"Ber.,  1913,  46:  2131;  1914,  47:  1881. 

12  Abs.  Z.  anal.  Chem.,  1887,  26:  100;  1888,  27:  232;  Chem.  Ztg.,  1898,  22:  4.37; 
U.  S.  Bur.  Chem.  Circ.  63;  Green.  The  Identification  of  Dyestuffs  on  Animal  Fibres. 
Rev.  ed.,  1913. 

1'  Ber.,  1888,  21:  3471. 

"  U.  S.  Bur.  Chem.  Circ.  114. 

i^Form^nek.  Spektralanalytischer  Nachweiss  kunstlicher  Organischer  Farb- 
stoffe  zum  Gebrauche  bei  wissenschaftlichen  und  gewerblichen  Untersuchungen. 
1900;  Formanek  und  Grandmougin.  Untersuchung  und  Nachweiss  Organischer 
Farbstoffe  auf  Spectroskopischem  Wege.     2nd  ed.,  1908-13. 

1^  Knecht  and  Hibbert.     New  Reduction  Methods  in  Volumetric  Analysis.     1910. 

1'  U.  S.  Bur.  Chem.  Circs.  25  and  63;  Allen.  Commercial  Organic  Analysis.  4th 
ed.,  1909-14,  5;  Leach.     Food  Inspection  and  Analysis.     3rd  ed.,  1913. 

18  Rupe.     Die  Chemie  der  Natiirlichen  Farbstoffe.     1900-09. 

1'  Willstatter  and  Stoll.  LTntersuchungen  liber  Chlorophyll,  Methoden  und 
Ergebnisse.     1913. 

^oSitz.  preuss.  Akad.,  1914,  12:  402. 

"  Ber.  botan.  Ges.,  1896,  14:  16;  Willstatter  and  Stoll.  Untersuchungen  Uber 
Chlorophyll,  Methoden  und  Ergebnisse.     1913. 

-2  Leach.     Food  Inspection  and  Analysis.     3rd  ed.,  1913,  p.  536. 

2'  Girard  and  Dupre.  Analyse  des  Matieres  Alimentaires  et  Re>cherches  de  leur 
Falsification.     1894. 


XII.     METALS  IN  FOODS. 
ARSENIC^.— TENTATIVE. 

1  REAGENTS. 

(a)  Nitric  and  sulphuric  acids,  arsenic-free. — Specific  gravities  1.42  and  1.S4, 
respectively. 

(b)  Stdphuric  acid  (1  to  2). 

(C)  Zinc,  arsenic-free. — Stick  zinc  broken  into  pieces  approximately  1  cm.  in 
length. 

(d)  Lead  acetate  paper. — Heavy  filter  paper  soaked  in  20%  lead  acetate  solution, 
dried  and  cut  into  pieces  about  4.5  by  16  cm. 

(e)  Lead  acetate  cotton. — Absorbent  cotton  soaked  in  5%  lead  acetate  solution. 

(f)  Mercuric  bromid  paper. — Cut  heavy,  close-textured  drafting  paper  (similar 
to  Whatman's  cold  pressed)  into  strips  exactly  2.5  mm.  wide  and  about  12  cm.  long. 
Soak  for  an  hour  in  a  5%  solution  of  mercuric  bromid  in  95%  alcohol,  squeeze  out 
the  excess  of  solution  and  dry  on  glass  rods.  Cut  off  the  ends  of  the  strips  before 
using. 

(g)  20%  potassium  iodid  solution. 

(h)  Stannous  chlorid  solution. — Forty  grams  of  stannous  chlorid  crystals  made  up 
to  100  cc.  with  concentrated  hydrochloric  acid. 

(i)  Standard  arsenic  solution. — Dissolve  1  gram  of  arsenious  oxid  in  25  cc.  of  20% 
sodium  hydroxid  solution,  neutralize  with  dilute  sulphuric  acid,  add  10  cc.  of  the 
concentrated  sulphuric  acid  and  dilute  to  1  liter  with  recently  boiled  water.  One 
cc.  of  this  solution  contains  1  mg.  of  arsenious  oxid  (AS2O3). 

Dilute  20  cc.  of  this  solution  to  1  liter.  Fifty  cc.  of  the  latter  solution  when 
diluted  to  1  liter  give  a  dilute  standard  solution  containing  0.001  mg.  of  arsenious 
o.xid  (AS2O3)  per  cc.  which  is  used  to  prepare  the  standard  stains.  The  dilute  solu- 
tions must  be  freshly  prepared  immediatel}'  before  use. 

2  APPAR.\TUS. 

Use  a  2  ounce  wide-mouthed  bottle  as  a  generator.  Fit  this  by  means  of  a  per- 
forated rubber  stopper  with  a  glass  tube,  diameter  1  cm.  and  6  cm.  long,  containing 
a  piece  of  the  lead  acetate  paper  rolled  into  a  cylinder.  Connect  this  tube  by  means 
of  a  perforated  rubber  stopper  with  a  similar  tube  filled  with  the  lead  acetate  cotton, 
squeezed  to  remove  excess  of  the  solution.  The  cotton  in  all  tubes  used  should  be 
uniformly  moist  to  obtain  comparative  stains.  Connect  the  second  tube  by  means 
of  a  perforated  rubber  stopper  with  a  narrow  glass  tube,  internal  diameter  3  mm. 
and  12  cm.  long,  containing  a  strip  of  the  mercuric  bromid  paper.  See  Fig.  7.  Rubber 
stoppers  used  for  connections  must  be  free  from  any  white  coating. 

3  PREPARATION   OF  SOLUTION. 

Weigh  5-50  grams  of  the  finely  divided  and  well  mixed  sample  into  a  porcelain 
casserole,  the  amount  selected  depending  upon  the  character  of  the  material  and  the 
ease  with  which  it  is  oxidized.  With  dry,  highly  nitrogenous  substances  employ 
5  grams;  pulped  vegetables,  25  grams;  liquids  with  low  solid  content  like  beer  or 

171 


172 


METHODS    OF   ANALYSIS 


[Chap. 


vinegar,  50  grams.  Add  10-15  cc.  of  the  nitric  acid,  cover  the  casserole  by  setting 
a  watch  glass  inside  the  rim,  convex  side  upward,  heat  until  vigorous  action  is 
over,  cool  and  add  10  cc.  of  the  concentrated  sulphuric  acid.  Heat  on  a  wire  gauze 
over  a  flame  until  the  mixture  turns  dark  brown  or  black,  then  add  more  nitric  acid 
in  5  cc.  portions,  heating  between  each  addition  until  the  liquid  remains  colorless 
or  yellow  when  evaporated  imtil  sulphur  trioxid  fumes  are  evolved.     To  remove 


FIG.  7.    APPARATUS  FOR  THE  DETERMINATION  OF  ARSENIC. 

completely  all  nitric  or  nitrous  acid,  evaporate  to  about  5  cc,  cool,  dilute  with  10- 
15  cc.  of  water  and  again  evaporate  until  white  fumes  are  evolved.  Cool,  dilute  with 
water,  again  cool,  and  make  up  with  water  to  a  definite  volume  (usually  25-100  cc, 
depending  upon  the  amount  of  sample  taken  and  its  arsenic  content). 


DETERMINATION. 


Introduce  20  cc.  of  the  solution  or,  if  the  amount  of  arsenic  is  large,  an  aliquot 
containing  not  more  than  0.03  mg.  of  AS2O3,  prepared  as    directed  in  3,  into  th« 


XII]  METALS   IN    FOODS  173 

generator  of  the  apparatus  described  in  2  and  add  20  cc.  of  the  dilute  sulphuric  acid. 
If  the  total  volume  is  less  than  40  cc,  dilute  to  that  volume  with  water  and  add 

4  cc.  of  the  20%  potassium  iodid  solution.  Heat  to  about  OO^C,  add  3  drops  of 
the  stannous  chlorid  solution  and  heat  for  10  minutes.  Cool  the  generator  and  its 
contents  in  a  pan  containing  water  and  ice;  when  cold  add  about  15  grams  of  the 
stick  zinc  and  connect  the  entire  apparatus  as  described  in  2.  Keep  the  bottles  in 
ice  water  for  15  minutes,  then  remove  from  the  bath  and  allow  the  evolution  of  gas 
to  proceed  for  an  hour  longer.  Remove  the  sensitized  paper  and  compare  the  stain 
with  similar  ones  produced  under  like  conditions  with  known  amounts  of  arsenic, 
using  portions  of  the  standard  arsenic  solution,  containing  0.001,  0.002,  0.005,  0.010, 
0.015,  0.025  and  0.030  mg.  of  arsenious  oxid  (AS2O3),  and  adding  such  quantities  of 
water  and  sulphuric  acid  that  the  same  volume  and  acid  strength  are  maintained  as 
above. 

TIN^ 

5  Gravimetric  Method. — Tentative. 

Weigh  50-100  grams  of  the  sample  (depending  upon  the  amount  of  dry  substance 
present  and  the  relative  ease  with  which  the  organic  matter  is  o.xidized)  into  an  800 
cc.  Kjeldahl  flask  and  add  100  cc.  of  concentrated  nitric  acid.  Allow  to  stand  over- 
night (this  procedure  being  preferred  if  much  fat  or  sugar  is  present)  or  else  place 
the  flask  on  a  wire  gauze  over  a  free  flame  and  heat  until  the  contents  boil  quietly. 
Add  25-50  cc.  of  concentrated  sulphuric  acid  (depending  upon  the  amount  of  dry 
substance  present  in  the  sample),  and  heat  until  white  fumes  are  generated,  cool 
somewhat,  then  add  5-10  cc.  of  concentrated  nitric  acid  and  continue  heating  as 
before.  Repeat  the  addition  of  nitric  acid  until  the  solution  remains  clear  after 
boiling  off  the  nitric  acid  and  fumes  of  sulphur  trioxid  appear. 

Add  200  cc.  of  water  to  the  digested  sample,  prepared  as  directed  above,  and  pour 
into  a  600  cc.  beaker.  Rinse  out  the  Kjeldahl  flask  with  3  portions  of  boiling  water 
so  that  the  total  volume  of  the  solution  is  about  400  cc.  Cool,  add  concentrated 
ammonia  until  just  alkaline  and  then  hydrochloric  or  sulphuric  acid  until  the  acidity 
is  about  2%.  Place  the  beaker,  covered,  on  a  hot  plate,  heat  to  about  95°C.  and  pass 
in  a  slow  stream  of  hydrogen  sulphid  for  another  hour.  Digest  on  the  hot  plate  for  an 
hour  and  allow  to  stand  1-2  hours  longer. 

Filter  the  tin  sulphid  on  an  11  cm.  filter,  similar  in  quality  to  No.  590,  white  ribbon, 
S.  &  S.  Wash  alternately  with  3  portions  each  of  wash  solution  (100  cc.  of  saturated 
ammonium  acetate  solution,  50  cc.  of  glacial  acetic  acid  and  850  cc.  of  water)  and 
hot  water.  Digest  the  filter  and  precipitate  in  a  50  cc.  beaker  with  3  successive 
portions  of  ammonium  polysulphid,  heat  to  boiling  each  time  and  filter  through  a 
9  cm.  filter.  Wash  the  precipitate  on  the  filter  with  hot  water.  Acidify  the  filtrate 
with  acetic  acid,  digest  on  a  hot  plate  for  an  hour,  allow  to  stand  overnight  and 
filter  through  a  double  11  cm.  filter.  Wash  alternately  with  2  portions  each  of  the 
wash  solution  and  hot  water  and  dry  thoroughly  in  a  weighed  porcelain  crucible. 
Ignite  over  a  Bunsen  flame,  very  gently  at  first  and  later  at  full  heat.  The  cru- 
cible, partly  covered,  is  then  heated  strongly  with  a  large  or  Meker  burner.  Stan- 
nic sulphid  must  be  roasted  gently  to  the  oxid,  which  may  be  heated  strongly  with- 
out loss  by  volatilization.     Weigh  as  stannic  oxid  and  calculate  to  metallic  tin. 

Volumetric  Method^. — Tentative. 

6  RE.\GENTS. 

(a)  Air-free  wash  solution. — Dissolve  20  grams  of  sodium  bicarbonate  in  2  liters 
of  boiled  water  and  add  40  cc.  of  concentrated  hydrochloric  acid.  This  solution 
should  be  freshly  prepared  before  use. 


174  METHODS    OF   ANALYSIS  [Chap. 

(b)  N / 100  iodin.— The  solution  must  be  standardized  frequently  against  (d),  con- 
taining asbestos,  and  treated  as  described  in  7,  omitting  the  precipitation  and  boil- 
ing with  hydrochloric  acid  and  potassium  chlorate.  To  obtain  exact  results  the 
tin  solution  used  for  standardization  should  contain  about  the  same  amount  of  tin 
as  is  found  in  the  sample  under  examination. 

(C)  N/100  sodium  thiosulphate. 

(d)  Standard  tin  solution. — Dissolve  1  gram  of  tin  in  about  500  cc.  of  concen- 
trated hydrochloric  acid.  Make  up  to  1  liter  with  water.  One  cc.  contains  1  mg. 
of  tin. 

(e)  Sheet  aluminium. — Use  sheet  aluminium,  about  30  gauge,  free  from  tin. 

7  DETERMINATION. 

Proceed  as  directed  in  5  to  "Digest  on  the  hot  plate  for  an  hour  and  allow  to 
stand  1-2  hours  longer". 

Filter  the  precipitate  of  tin  sulphid  upon  asbestos  in  a  Gooch  crucible  with  a 
detachable  bottom,  using  suction.  Wash  the  precipitate  a  few  times  and  then 
transfer  the  detachable  bottom,  asbestos  pad,  and  tin  precipitate  to  a  300  cc.  Er- 
lenmeycr  flask.  Remove  all  traces  of  the  precipitate  from  the  inside  of  the  cru- 
cible by  means  of  a  jet  of  hot  water  and  a  policeman,  using  a  minimum  amount  of 
water  for  washing. 

Add  100  cc.  of  concentrated  hydrochloric  acid  and  0.5  gram  of  potassium  chlorate 
to  the  flask.  Boil  for  about  15  minutes,  making  about  4  more  additions  of  smaller 
amounts  of  potassium  chlorate  as  chlorin  is  boiled  out  of  the  solution.  Wash  the 
particles  of  potassium  chlorate  down  from  the  neck  of  the  flask  with  water  and 
finally  boil  to  remove  chlorin.  Then  add  about  1  gram  of  the  sheet  aluminium  to 
dispel  the  last  traces  of  chlorin. 

Attach  the  flasks,  in  duplicate,  as  described  below,  to  a  large  carbon  dioxid  gener- 
ator. Pass  the  carbon  dioxid  through  a  scrubber  containing  water  and  then  divide 
into  2  streams  by  means  of  a  Y-tube,  each  stream  of  carbon  dioxid  entering  one  of 
the  flasks  by  means  of  a  long  rubber  tube  connected  with  a  bulbed  tube,  passed 
through  the  rubber  stopper  of  the  flask  and  having  its  lower  end  near  the  surface  of 
the  liquid  in  the  flask.  The  carbon  dioxid  leaves  the  flask  by  a  second  bulbed  tube, 
the  opening  of  which  is  near  the  top  of  the  flask.  This  glass  tube  is  connected  by  a 
long  rubber  tube  to  a  second  glass  tube  about  10  inches  long  which  is  immersed  in  a 
cylinder  containing  water.  This  gives  a  water-seal  to  the  delivery  tube  and  a  pres- 
sure against  which  the  current  of  carbon  dioxid  must  work.  It  also  restrains  any 
strong  flow  of  gas  when  not  desired  and  permits  a  gas  pressure  in  the  Erlenmeyer 
flask. 

After  the  flasks  are  connected,  raise  the  tubes  in  the  water-seal  cylinders  so  that 
the  generator  has  practically  no  pressure  to  overcome.  Allow  the  carbon  dioxid 
to  run  for  a  few  minutes.  Drop  the  tubes  to  the  bottom  of  the  cylinders,  creating 
pressure  in  the  flasks.  Lift  the  rubber  stoppers  of  the  flasks  alternately  about  a 
dozen  times,  in  order  to  force  out  any  air  remaining  in  the  flasks.  Slightly  raise  the 
stopper  on  one  of  the  flasks  and  quickly  drop  about  2  grams  of  sheet  aluminium  into 
the  flask.  The  aluminium  should  be  folded  into  a  strip  about  1  cm.  wide  and  slightly 
bent  so  as  to  prevent  it  from  striking  directly  on  the  bottom  of  the  flask.  After 
the  aluminium  has  entirely  dissolved,  raise  the  tubes  in  the  water-seal  cylinders  so 
as  to  allow  carbon  dioxid  to  pass  through,  place  the  flasks  upon  hot  plates,  and  heat 
to  boiling.  After  boiling  for  a  few  minutes,  remove  the  flasks  from  the  hot  plates 
and  cool  in  ice  water  (or  cold  running  water),  still  maintaining  within  them  an 


XII]  METALS    IN    FOODS  175 

atmosphere  of  carbon  dioxid.  Lower  the  tubes  in  the  cylinder.  When  cool,  dis- 
connect the  flasks  one  at  a  time,  putting  a  glass  plug  into  the  carbon  dioxid  inflow. 
Wash  the  tubes,  rubber  stopper  and  sides  of  the  flask  with  the  air-free  wash  solution, 
add  starch  paste  and  titrate  at  once  with  the  N/100  iodin. 

If  it  is  desired  to  titrate  by  the  excess  method,  run  an  excess  of  the  N/100  iodin 
into  the  flask  while  it  is  still  connected  with  the  carbon  dioxid  stream.  Then  wash 
out  the  tubes  and  titrate  the  excess  of  iodin  with  the  N/100  sodium  thiosulphate. 

The  rubber  connections  should  be  washed  with  water  after  each  determination. 

8  COPPER.— TENTATIVE. 

Destroy  organic  matter  as  directed  in  5.  Concentrate  the  sulphuric  acid  residue 
by  continued  digestion  to  a  volume  of  10-15  cc,  cool,  dilute  with  a  little  water,  trans- 
fer to  a  400  cc.  beaker,  rinse  the  Kjeldahl  flask  with  water,  adding  the  rinsings  to  the 
contents  of  the  beaker,  dilute  to  about  200  cc.  and  boil  to  expel  nitrous  fumes.  Cool, 
render  the  solution  slightly  alkaline  with  ammonium  hydroxid  and  boil  to  expel  the 
excess  of  ammonia.  Add  5  cc.  of  concentrated  hydrochloric  acid  for  each  100  cc. 
of  solution,  heat  to  incipient  boiling  and  saturate  the  solution  with  hydrogen  sul- 
phid.  Allow  to  stand  on  a  steam  bath  for  a  few  minutes  until  the  sulphid  flocculates, 
filter  and  wash  the  precipitate  with  hydrogen  sulphid  water.  Protect  the  precipi- 
tate from  contact  with  air  as  much  as  possible,  use  only  hydrogen  sulphid  water  for 
washing  and  carry  out  this  operation  without  interruption.  Reserve  the  filtrate 
for  the  determination  of  zinc,  if  necessary.  Place  the  filter  containing  the  copper 
sulphid  precipitate  in  a  small  flask,  add  4-5  cc.  of  concentrated  sulphuric  acid  and 
the  same  amount  of  nitric  acid  and  heat  until  white  fumes  appear.  Continue  the 
oxidation,  adding  a  little  nitric  acid  from  time  to  time,  until  the  liquid  remains 
colorless  upon  heating  to  the  appearance  of  white  fumes.  Cool,  dilute  with  about 
30  cc.  of  water,  add  an  excess  of  bromin  water  and  boil  until  all  bromin  is  expelled. 
Determine  the  copper  as  directed  in  VIII,  29,  using  N/100  sodium  thiosulphate  for 
the  titration. 

9  ZINC— TENTATIVE. 

Proceed  as  directed  in  8  to  the  point  indicated  by  the  sentence  "Reserve  the  fil- 
trate for  the  determination  of  zinc,  if  necessary".  Boil  the  filtrate,  containing  the 
zinc,  to  expel  hydrogen  sulphid  and  to  reduce  the  volume  to  about  250-300  cc,  add 
a  drop  of  methyl  orange  and  5  grams  of  ammonium  chlorid  and  make  alkaline  with 
ammonium  hydroxid.  Add  dilute  hydrochloric  acid,  drop  by  drop,  until  the  re- 
action is  faintly  acid,  then  add  10-15  cc.  of  50%  sodium  or  ammonium  acetate  solu- 
tion and  pass  in  hydrogen  sulphid  for  a  few  minutes  until  precipitation  is  complete. 
Allow  the  precipitate  to  settle,  filter,  refilter,  if  necessary,  until  the  filtrate  is  clear, 
and  wash  the  precipitate  twice  with  hydrogen  sulphid  water.  Dissolve  the  precipi- 
tate on  the  filter  with  a  little  hydrochloric  acid  (1  to  3),  wash  the  filter  with  water, 
boil  the  filtrate  and  washings  to  expel  hj'drogen  sulphid,  cool  and  add  a  distinct 
excess  of  bromin  water.  Then  add  5  grams  of  ammonium  chlorid  and  ammonium 
hydroxid  until  the  color,  caused  by  free  bromin,  disappears.  Add  hydrochloric 
acid  (1  to  3),  drop  by  drop,  until  the  bromin  color  just  reappears,  then  add  10-15  cc. 
of  50%  sodium  or  ammonium  acetate  solution  and  0.5  cc.  of  10%  ferric  chlorid  solu- 
tion, or  enough  to  precipitate  all  the  phosphates.  Boil  until  all  the  iron  is  precipi- 
tated. Filter  while  hot  and  wash  the  precipitate  with  water  containing  a  little 
sodium  acetate.     Pass  hydrogen  sulphid  into    the  combined  filtrate  and  washings 


176  METHODS    OF   ANALYSIS 

until  all  the  zinc  sulphid,  which  should  be  pure  white,  is  precipitated,  filter  upon  a 
tared  Gooch  and  wash  with  hydrogen  sulphid  water,  containing  a  little  ammonium 
nitrate.  Dry  the  crucible  and  its  contents  in  an  oven,  ignite  at  a  bright  red  heat, 
cool  and  weigh  as  zinc  oxid.     Calculate  the  weight  of  metallic  zinc. 

BIBLIOGRAPHY. 

1  U.  S.  Bur.  Chem.  Circ.  102;  J.  Soc.  Chem.  Ind.,  1907,  26:  1115. 

2  J.  Assoc.  Official  Agri.  Chemists,  1915,  1:  257. 

^Proc.  Eighth  Intern.  Cong.  Appl.  Chem.,  1912,  18:  35. 


Xm.     FRUITS  AND  FRUIT  PRODUCTS. 

1  PREPARATION  OF  SAMPLE— TENTATIVE. 

All  samples  received  in  open  packages  (i.e.,  not  in  sterile  condition)  must  be  trans- 
ferred without  delay  to  glass-stoppered  containers  and  kept  in  a  cool  place.  The 
determination  of  alcohol,  total  and  volatile  acids,  solids  and  sugars,  particularly 
in  the  case  of  fruit  juices  and  fresh  fruits,  should  be  made  at  once  as  fermentation 
is  liable  to  begin  very  soon.  Portions  for  the  determinations  of  sucrose  and  reducing 
sugar  may  be  weighed  and,  after  adding  a  slight  excess  of  neutral  lead  acetate  solu- 
tion, kept  without  fermenting  for  several  days  if  desired.  The  various  products 
are  prepared  as  directed  below. 

(a)  Juices. — Prepare  the  fresh  juice  by  pressing  the  well  pulped  fruit  in  a  jelly 
bag  and  filtering  through  muslin. 

(b)  Jellies  and  sirups. — Mix  thoroughly  to  insure  uniformity  in  sampling.  Weigh 
60  grams  into  a  300  cc.  flask,  add  water,  dissolve  by  frequent  shaking,  then  make  up 
to  the  mark  with  water,  and  use  aliquots  for  the  various  determinations.  If  the 
jelly  contains  starch  or  other  insoluble  material,  mix  thoroughly  before  taking  the 
aliquots. 

(C)  Fresh  and  dried  fruits. — Pulp  the  whole,  well  cleaned  fruit  in  a  large  mortar  or 
by  means  of  a  food  chopper  and  mix  thoroughly.  In  the  case  of  stone  fruits,  remove 
the  pits  and  determine  their  proportion  in  a  weighed  sample. 

(d)  Jams,  marmalades,  preserves  and  canned  fruits. — Pulp  thoroughly  the  entire 
contents  of  the  jar  or  can,  as  directed  under  (C);  with  stone  fruits  remove  the  pits 
and,  if  desired,  determine  their  proportion  in  a  weighed  sample.  In  the  exami- 
nation of  canned  fruits  it  is  often  sufficient  merely  to  examine  the  sirups  in  which  the 
fruits  are  preserved.  In  such  cases  the  liquor  may  be  separated  and  treated  as  pre- 
scribed for  juices. 

2  ALCOHOL.-TENTATIVE. 

Determine  alcohol  in  50  grams  of  the  original  material  as  directed  under  IX,  31 . 

3  TOTAL  SOLIDS.— TENTATIVE. 

(a)  Juices,  jellies  and  sirups  containing  no  insoluble  matter. — Proceed  as  di- 
rected in  IX,  3,  5,  7  or  10,  employing  the  sample  prepared  as  directed  in  1  (a)  or  (b). 

(b)  Fresh  and  dried  fruits,  jams,  marmalades,  preserves,  canned  foods  and  other 
products  containing  insoluble  matter. — Weigh  about  20  grams  of  pulped  fresh  fruit, 
or  such  an  amount  of  fruit  products  as  will  give  not  more  than  3-4  grams  of  dried 
material;  if  necessary  to  secure  a  thin  layer  of  the  material,  add  a  few  cc.  of  water, 
mix  thoroughly,  and  dry  as  directed  in  DC,  3  or  4. 

It  is  to  be  noted  that  certain  State  and  Federal  regulations  require  the  moisture 
in  dried  apples  to  be  determined  by  drying  for  4  hours  at  the  temperature  of  boiling 
water. 

INSOLUBLE  SOLIDS. 

4  Direct  Method.— Tentative. 

Transfer  50  grams  of  the  sample  to  a  mortar  by  means  of  warm  water  and  macerate 
thoroughly;  then  transfer  to  a  muslin  filter  and  wash  thoroughly  with  about  500  cc. 
of  warm  water,  stirring  the  pulp  thoroughly  on  each  addition  of  water.  This  amount 
of  water  is  usually  sufficient  to  remove  all  soluble  material.     In  extreme  cases  increase 

177 


178  METHODS    OF   ANALYSIS  [Chap. 

the  washings  to  1000  cc.  Transfer  the  insoluble  residue  to  an  evaporating  dish,  dry 
and  weigh.  If  it  is  desired  to  determine  the  alcohol  precipitate,  18,  cool  the  filtrate, 
make  up  to  a  definite  volume  and  reserve  for  this  determination. 

5  Indirect  Method. — Tentative. 

Transfer  25  grams  of  the  fruit  product  to  a  250-500  cc.  graduated  flask,  the  size 
of  the  flask  depending  upon  the  volume  of  insoluble  matter  present,  add  water, 
shake  thoroughly  and  make  up  to  volume.  Allow  to  settle  and  either  filter  or  decant 
the  supernatant  liquid.  Determine  the  soluble  solids  in  an  aliquot,  as  directed  in 
3  (a).  The  fruit  must  be  macerated  thoroughly;  the  use  of  a  mechanical  shaker  is 
advisable.  The  percentage  of  insoluble  solids  is  the  difference  between  the  per- 
centage of  the  total  solids  and  the  percentage  of  soluble  solids. 

6  TOTAL  ASH.— OFFICLO-. 

Determine  the  ash  as  directed  under  VIII,  4,  using  50  cc.  of  the  solution  of  the 
jelly  or  diluted  sirup,  1  (b),  evaporated  to  dryness,  or  25  grams  of  juice  or  of  fresh 
or  canned  fruit,  or  10  grams  of  jam,  marmalade,  preserves,  or  dried  fruit. 

7  ALKALINITY  OF  THE  ASH.— TENTATIVE. 

Into  the  platinum  dish  containing  the  ash  introduce  a  measured  excess  of  N/5 
nitric  acid,  heat  to  boiling,  cool  and  add  a  few  drops  of  methyl  orange.  Carefully 
rub  up  the  ash  with  a  rubber-tipped  stirring  rod  and  titrate  the  excess  of  acid  with 
N/10  potassium  or  sodium  hydroxid.  Express  the  result  as  the  number  of  cc.  of 
N/10  acid  required  to  neutralize  the  ash  from  100  grams  of  the  sample. 

8  SULPHATE  AND  CHLORID.-TENTATIVE. 

Wash  the  solution  of  the  ash,  obtained  in  7,  into  a  50  cc.  flask  and  make  up  to  the 
mark  with  water.  Evaporate  25  cc.  of  this  solution  to  dryness  several  times  with  con- 
centrated hydrochloric  acid,  take  up  the  final  residue  in  a  small  amount  of  hot  water, 
filter,  wash  the  paper  with  hot  water,  acidify  the  filtrate  with  a  few  drops  of  hydro- 
chloric acid  and  determine  the  sulphate  by  precipitation  with  barium  chlorid 
solution.  From  the  weight  of  barium  sulphate  calculate  the  sulphate  present  as 
per  cent  of  potassium  sulphate. 

In  the  other  portion  of  the  solution  determine  the  chlorin  as  directed  under  III,  15. 
The  nitric  acid  added  before  making  the  titration  will,  if  it  contain  enough  nitrous 
oxid,  completely  destroy  the  red  color  of  the  methyl  orange  and  leave  a  clear  solu- 
tion for  the  titration.     Calculate  the  chlorin  as  per  cent  of  sodium  chlorid. 

9  TOTAL  ACIDITY.— TENTATIVE. 

Dilute  25  cc.  of  the  solution  of  jelly  or  diluted  sirup,  1  (b),  or  10  grams  of  juice  or 
fresh  fruit,  with  recently  boiled  water  to  about  250  cc,  or  less  if  the  sample  be  not 
highly  colored;  titrate  the  acid  with  N/10  alkali,  using  phenolphthalein  as  an  in- 
dicator. In  the  case  of  highly  colored  products  employ  azolitmin  solution  or  phenol- 
phthalein powder  [XVI,  25]  on  a  spot  plate  instead  of  phenolphthalein  solution. 
Calculate  the  results  as  malic,  citric  or  tartaric  acid,  specifying  the  acid  used  and 
expressing  the  results  in  grams  per  100  cc. 

10  VOLATILE  ACIDS.— TENTATIVE. 

Dissolve  10  grams  of  tlie  sample,  dilute  to  25  cc.  and  distil  in  a  current  of  steam, 
as  directed  under  XVI,  27.  Each  cc.  of  N/10  alkali  is  equivalent  to  0.0060  gram  of 
acetic  acid. 


XIII]  FRUITS   AXD    FRUIT   PRODUCTS  179 

11  FREE  MINERAL  ACIDS.— TENTATIVE. 
Proceed  as  directed  under  XIX,  26,  27  or  28. 

12  PROTEIN.— OFFICIAL. 

Proceed  as  directed  under  I,  18,  21  or  23,  using  5  grams  of  jell}'  or  other  fruit 
product  containing  a  large  amount  of  sugar,  or  10  grams  of  juice  or  fresh  fruit  and 
a  larger  quantity  of  the  sulphuric  acid  if  necessary  for  complete  digestion.  Multi- 
ply the  percentage  of  nitrogen  by  6.25  to  obtain  the  percentage  of  protein. 

SUCROSE. 

13  By  Polarization. — Official. 

Determine  by  polarizing  before  and  after  inversion,  as  directed  under  IX,  22  or  23. 

14  By  Reducing  Sugars  Before  and  After  Inversion. — Tentative. 
Proceed  as  directed  under  VIII,  18. 

15  REDUCING   SUGARS.-TENTATIVE. 

Proceed  as  directed  under  VIII,  25,  expressing  the  results  as  invert  sugar. 

16  COMMERCLA.L   GLUCOSE.— TENTATIVE. 
Proceed  as  directed  under  IX,  25. 

1 7  DEXTRIN.— TENTATIVE. 

Dissolve  10  grams  of  the  sample  in  a  100  cc.  flask,  add  20  mg.  of  potassium  fluorid, 
and  then  about  one  fourth  of  a  cake  of  compressed  yeast.  Allow  the  fermentation 
to  proceed  below  2o°C.  for  2-3  hours  to  prevent  excessive  foaming,  and  then  incu- 
bate at  27°-30°C.  for  5  days.  At  the  end  of  that  time,  clarify  with  basic  lead  acetate 
solution  and  alumina  cream,  make  up  to  100  cc.  and  polarize  in  a  200  mm.  tube. 
A  pure  fruit  jelly  will  show  a  dextro  or  laevo-rotation  of  not  more  than  a  few  tenths 
of  a  degree.  If  a  polariscope  having  the  Ventzke  scale  be  used  and  a  10%  solution 
polarized  in  a  200  mm.  tube,  the  number  of  degrees  read  on  the  sugar  scale  of  the  in- 
strument multiplied  by  0.8755  will  give  the  percentage  of  dextrin,  or  the  following 
formula  may  be  used: 

C  X  100 

Percentage  of  dextrin  =  in  which 

198  X  L  X  W 
C  =  degrees  of  circular  rotation; 
L  =  length  of  tube  in  decimeters; 
W  =  weight  of  sample  in  1  cc. 

18  ALCOHOL  PRECrPITATE.-TENTATIVE. 

Evaporate  100  cc.  of  a  20%  solution  of  jelly  or  diluted  sirup,  1  (b),  or  of  the  wash- 
ings from  the  determination  of  insoluble  solids,  4,  to  20  cc. ;  add  slowly,  with  constant 
stirring,  200  cc.  of  95%  alcohol  by  volume  and  allow  the  mixture  to  stand  overnight. 
Filter  and  wash  with  80%  alcohol  by  volume.  Wash  the  precipitate  from  the 
filter  paper  with  hot  water  into  a  platinum  dish;  evaporate  to  dryness;  dry  at  lOCC. 
for  several  hours  and  weigh;  then  burn  off  the  organic  matter  and  weigh  the  residue 
as  ash.     Designate  the  loss  in  weight  upon  ignition  as  the  alcohol  precipitate. 

The  ash  should  be  chiefly  lime  and  not  more  than  5%  of  the  total  weight  of  the 
alcohol  precipitate.  If  it  is  greater  than  this,  some  of  the  salts  of  the  organic  acids 
have  been  brought  down.  Titrate  the  water-soluble  portion  of  this  ash  with  N'lO 
acid,  as  any  potassium  bitartrate  precipitated  by  the  alcohol  can  thus  be  estimated. 


180  METHODS   OF   ANALYSIS  [Chap. 

STARCH. 

19  Qualitative  Test. — Tentative. 

First  destroy  the  color  of  the  jelly  by  treatment  with  sulphuric  acid  and  potassium 
permanganate  solution  and  then  test  with  iodin  solution.  Bring  the  solution  of 
jelly  nearly  to  boiling,  add  several  cc.  of  dilute  sulphuric  acid  and  then  potassium 
permanganate  solution  until  all  color  is  destroyed.  The  starch  remains  unaffected 
by  this  treatment.  The  presence  of  starch  is  not  necessarily  an  indication  of  its 
addition  as  an  adulterant.  It  is  usually  present  in  small  amount  in  the  apple,  and 
occasionally  in  other  fruits,  and  unless  it  is  found  in  the  fruit  product  in  consider- 
able amount  its  presence  may  be  due  to  these  natural  sources. 

GELATINi. 

20  Qualitative  Test. — Tentative. 

The  presence  of  gelatin  in  jellies  and  jams  is  shown  by  the  increased  content  of 
nitrogen.  Precipitate  a  concentrated  solution  of  jelly  or  jam  with  10  volumes  of 
absolute  alcohol  and  determine  nitrogen  in  the  dried  precipitate  as  directed  under 

I,  18,  21  or  23. 

AGAR  AGAR. 

QUALITATIVE  TESTS. 

21  By  Microscopic  Examination^. — Tentative. 

Heat  the  jelly  with  5%  sulphuric  acid,  add  a  crystal  of  potassium  permanganate 
and  allow  to  settle.  If  agar  agar  is  present  the  sediment  will  be  rich  in  diatoms 
which  can  be  detected  by  the  use  of  the  microscope. 

22  By  Precipitation^. — Tentative. 

Cover  30  grams  of  the  jam  or  jelly  with  270  cc.  of  hot  water,  stir  until  thoroughly 
disintegrated  and  boil  for  3  minutes.  Filter  immediately,  while  still  boiling  hot, 
through  a  filter  paper  of  texture  similar  to  No.  597,  S.  &  S.  In  the  presence  of  agar 
agar  a  precipitate  will  form  upon  standing  not  longer  than  24  hours.  Filter, 
wash  with  cold  water  and  dissolve  from  the  paper  by  means  of  a  very  small  amount 
of  boiling  water.  Upon  chilling  this  hot  water  solution  a  firm  jelly  will  be  formed 
that  can  be  examined  by  the  touch.  This  method  will  detect  0.2%  of  agar  agar  with 
certainty  if  the  proportions  of  jam  or  jelly  and  water  are  strictly  observed. 

TARTARIC  ACID.-TENTATIVE. 

23  PREPARATION   OF  SOLUTION. 

Filter  fruit  juices  and  employ  the  filtrate  directly.  In  the  case  of  jellies  filter 
the  solution,  prepared  as  directed  in  1  (b),  and  employ  the  filtrate.  In  the  case  of 
sirups  or  substances  containing  insoluble  matter  like  ptilped  fruit,  jams,  marmalades, 
etc.,  weigh  50-100  grams,  the  amount  selected  being  dependent  upon  the  content  of 
solids,  of  the  sample,  prepared  aS  directed  in  1  (C)  or  (d),  introduce  into  a  200  cc. 
graduated  flask,  make  up  to  the  mark  with  water,  allow  to  stand  for  an  hour,  shake  at 
frequent  intervals,  filter  through  a  dry  paper  and  use  the  filtrate. 

24  DETERMINATION. 

Determine  the  tartaric  acid  in  100  cc.  of  fruit  juice  or  the  same  amount  of  a  solu- 
tion of  the  sample,  prepared  as  directed  in  23,  employing  the  method  given  under  XVI, 
29,  except  that  20  cc.  of  alcohol  are  used  in  the  precipitation  instead  of  15  cc. 


XIII]  FRUITS   AND    FRUIT   PRODUCTS  181 

MALIC  ACID. 

25  Method  I.— Tentative. 

(For  fruit  juices  and  similar  products  containing  no  tartaric  acid  and  not 
over  15%  of  sugars  and  in  which  the  color  does  not  interfere 
with  polarization.) 

Filter  the  sample,  if  necessary  to  secure  a  solution  which  can  be  readily  polar- 
ized, and  polarize  with  white  light  and  a  dichromate  cell,  using  a  200  mm.  tube  if 
possible. 

If  the  sample  contains  free  mineral  acid,  transfer  a  measured  portion  (75  cc.  is  a 
convenient  volume)  to  a  100  cc.  graduated  flask,  add  enough  standard  alkali,  cal- 
culated from  the  acidity  as  determined  in  9,  to  neutralize  the  total  acidity,  dilute 
to  the  mark,  mix  well  and  filter.  If  no  free  mineral  acids  are  present,  it  is  unneces- 
sary to  neutralize  the  sample.  If  neutralized,  proper  correction  must  be  made  for 
dilution  in  making  the  final  calculation. 

Transfer  25  cc.  of  the  sample,  or  a  neutralized  solution,  to  a  flask  graduated  at  25 
and  27.5  cc,  add  about  2.5  grams  of  powdered  uranyl  acetate,  and  shake  vigorously 
at  frequent  intervals  for  3  hours,  keeping  the  mixture  well  protected  from  light. 
If  all  of  the  uranyl  acetate  dissolves,  add  more  so  that  a  small  amount  remains 
undissolved  at  the  end  of  3  hours.  Dilute  the  solution  to  the  27.5  cc.  mark  with 
saturated  uranyl  acetate  solution,  mix  well  and  filter,  if  necessary,  through  a  folded 
filter.  Polarize,  if  possible,  in  a  200  mm.  tube.  If  the  solution  is  too  dark  to  polarize 
in  a  200  mm.  tube,  a  100  or  50  mm.  tube  may  be  used.  Multiply  the  reading  by  1.1 
to  correct  for  the  dilution. 

Multiply  the  algebraic  difference  in  degrees  Ventzke  between  the  2  readings  cal- 
culated to  the  basis  of  a  200  mm.  tube  by  the  factor  0.036  to  obtain  the  weight  of 
malic  acid  in  the  sample  in  grams  per  100  cc. 

Make  all  polarizations  at  the  same  room  temperature  with  white  light  and  with 
a  dichromate  cell.  Make  at  least  6  readings  in  each  case  and  take  an  average  of 
these. 

In  the  case  of  dark  colored  fruit  juices  which  cannot  be  polarized  readily,  approxi- 
mately quantitative  results  may  be  obtained  by  adding  to  the  solutions  a  few  drops 
of  bromin,  shaking  thoroughly  and  filtering  just  before  polarization. 

Method  II. — Tentative. 

(Approximate  determination  for  fruit  juices  and  similar  products   con- 
taining no  tartaric  acid  and  more  than  15%  of  sugars.) 

26  PREPARATION  OF  SOLUTION^ 

Weigh  out  25  grams  of  the  sample  and  transfer  to  a  600  cc.  beaker  with  a  little 
95%  alcohol  by  volume.  Add  alcohol  a  little  at  a  time  until  200  cc.  have  been  added, 
stirring  the  mixture  well,  and  warming,  if  necessary,  to  insure  solution  of  all  alcohol- 
soluble  substances.  Filter  on  a  BUehner  funnel,  using  suction,  and  thoroughly 
wash  the  precipitated  pectins  and  insoluble  matter  with  95%  alcohol,  disregarding 
any  slight  turbidity  which  may  appear  in  the  filtrate  after  the  washings  have 
been  added.  From  9,  calculate  the  amount  of  N/4  barium  hydroxid  required 
nearly  to  neutralize  the  acidity  in  the  25  grams  of  sample  taken.  To  the  com- 
bined filtrate  and  washings  in  an  Erlenmeyer  flask  add  the  calculated  quantity  of 
barium  hydroxid  solution,  stir  until  reaction  is  complete  and  then  add  3-5  drops,  or 
more  if  required,  of  50%  barium  acetate  solution  to  insure  an  excess  of  barium. 
Make  up  the  volume  of  the  mixture  to  about  375  cc.  (not  less)  with  alcohol,  and  re- 
flux until  the  precipitate  settles  readily  after  being  shaken.     This  may  require  3—1 


182  METHODS    OF   ANALYSIS  [Chap. 

hours.  Filter  with  suction  and  thoroughly  wash  the  precipitate  in  the  flask  and 
on  the  paper  with  95%  alcohol  by  volume.  Transfer  the  portion  on  the  filter  to 
the  original  flask,  rinsing  the  paper  with  a  jet  of  hot  water.  Digest  the  pre- 
cipitate with  hot  water,  containing  2  grams  of  sodium  sulphate  in  solution,  un- 
til the  reaction  is  complete,  and  boil  until  the  barium  sulphate  precipitate  settles 
readily.  Concentrate  by  evaporation,  if  necessary,  and  transfer  to  a  100  cc.  vol- 
umetric flask  with  a  little  hot  water,  cool,  make  up  to  volume  with  water  and 
filter. 

27  DETERMINATION. 

Transfer  25  cc.  of  the  filtrate,  obtained  in  26,  to  a  flask  graduated  at  25  and 
27.5  cc,  add  about  2.5  grams  of  pulverized  uranyl  acetate  and  shake  vigorously  at 
frequent  intervals  for  3  hours,  keeping  the  solution  well  protected  from  light.  If  all 
the  uranyl  acetate  dissolves,  add  more  so  that  a  small  amount  remains  undissolved 
at  the  end  of  3  hours.  Dilute  the  solution  to  the  27.5  cc.  mark  with  saturated  uranyl 
acetate  solution,  mix  well,  filter  if  necessary,  and  polarize  in  a  200  mm.  tube,  using 
the  same  precautions  as  described  in  25.  Multiply  the  reading,  calculated  to  the 
basis  of  a  200  mm.  tube,  by  1.1  to  correct  for  the  dilution. 

Polarize  another  portion  of  the  filtrate,  obtained  in  26,  which  has  not  been  treated 
with  uranyl  acetate.  Multiply  the  algebraic  difference  in  degrees  Ventzke  between 
the  2  readings,  calculated  to  the  basis  of  a  200  mm.  tube,  by  the  factor  0.036  to  obtain 
the  weight  of  malic  acid  in  grams  per  100  cc.  in  the  solution  as  obtained  in  26. 

Method  III. — Tentative. 
(Approximate  determination  for  products  containing  tartaric  acid.) 

28  PREPARATION   OF  SOLUTION^. 

Prepare  the  sample  as  directed  under  26  up  to  the  point  of  filtration  and  washing 
of  the  barium  malate  precipitate,  then  dry  the  precipitate  thoroughly  and  transfer 
the  portion  on  the  filter  to  the  original  flask,  rinsing  the  paper  with  a  jet  of  hot 
water.  Digest  the  precipitate  with  hot  water,  transfer  to  a  100  cc.  volumetric 
flask  with  a  little  hot  water,  cool,  make  up  to  volume  with  water  and  filter  to  re- 
move insoluble  barium  tartrate.  This  amount  of  water  is  sufficient  to  dissolve 
barium  malate  up  to  amounts  as  large  as  approximately  0.9  gram  in  100  cc.  More 
than  100  cc.  of  water  must  be  used  when  more  than  0.9  gram  of  barium  malate 
is  present.  The  amount  of  barium  tartrate  dissolved  by  hot  water  is  so  small  as  to 
affect  only  slightly  the  polarization  after  treatment  with  uranyl  acetate. 

29  DETERMINATION. 

Proceed  as  directed  in  27,  using  the  solution  prepared  as  directed  in  28. 

CITRIC  ACID^— TENTATIVE. 
CApplicable  in  the  presence  of  sugar  and  malic  and  tartaric  acids.) 

30  REAGENTS. 

(a)  Barium  hydroxid  solulion. — Approximately  N/4. 

(b)  50%  barium  acetate  solution. 

(C)  Sulphuric  acid  (1  to  1)  and  (/  to  5). 

(d)  Potassium  or  sodium  broynid  solution. — Dissolve  15  grams  of  potassium  bromid 
in  40  cc.  of  water  or  16  grams  of  sodium  bromid  in  50  cc.  of  water. 


XIII]  FRUITS   AND    FRUIT   PRODUCTS  183 

(e)  6%  potassium  permanganate  solution. 

(f)  Ferrous  sulphate  solution. — Dissolve  20  grams  of  ferrous  sulphate  in  100  cc. 
of  water  containing  1  cc.  of  concentrated  sulphuric  acid. 

(g)  Bromin  water. — Freshly  prepared,  saturated  solution. 

31  DETERMINATION. 

Proceed  as  directed  in  26  up  to  "Filter  with  suction  and  thoroughly  wash  the 
precipitate  in  the  flask  and  on  the  paper  with  95%  alcohol  by  volume".  Transfer  the 
precipitate  from  the  filter  to  the  flask  with  a  jet  of  hot  water,  boil  until  alcohol 
can  no  longer  be  detected  by  odor,  and  add  enough  of  the  sulphuric  acid  (1 
to  5)  to  precipitate  all  the  barium  originally  added  and  to  allow  2  cc.  in  excess. 
Evaporate  by  careful  boiling  to  a  volume  of  60-70  cc,  cool  and  add  5  cc.  of  freshly 
prepared  saturated  bromin  water,  or  enough  to  show  a  distinct  excess.  Transfer 
with  water  to  a  100  cc.  volumetric  flask  and  dilute  to  the  mark  at  standard 
temperature.  Mix  thoroughly,  allow  the  precipitate  to  settle  and  filter  through 
a  dry  paper.  The  precipitate  may  be  separated  by  centrifugalizing  and  the  super- 
natant liquid  decanted,  if  necessary.  Pipette  an  aliquot  of  the  filtrate,  containing 
not  more  than  250  mg.  of  citric  acid,  calculated  from  the  total  acidity  of  the  sample, 
into  a  300  cc.  Erlenmeyer  flask.  If  possible,  the  amount  of  citric  acid  in  the  ali- 
quot should  exceed  50  mg.  Add  10  cc.  of  the  sulphuric  acid  (1  to  1)  and  5  cc.  of  the 
potassium  or  sodium  bromid  solution,  mix,  warm  the  flask  in  a  water  bath  to4S°-50°C. 
and  allow  it  to  remain  in  the  bath  for  5  minutes.  After  removing  from  the  bath  add 
rapidly  from  a  pipette,  drop  by  drop  with  frequent  interruptions,  25  cc.  of  the  5% 
potassium  permanganate  solution  and  shake  vigorously;  avoiding  a  temperature 
during  oxidation  exceeding  55°C.  Set  the  flask  aside  until  the  hydrated  peroxid  of 
manganese  begins  to  settle.  The  supernatant  liquid  should  be  dark  brown,  showing 
an  excess  of  permanganate;  if  an  excess  is  not  indicated,  add  more  permanganate. 
Shake,  again  set  aside  to  settle  and  repeat  this  operation  until  the  precipitate 
assumes  a  yellow  color  and  most  of  it  has  dissolved.  Finally,  while  the  solution 
is  still  warm,  remove  the  last  undissolved  portion  of  hydrated  peroxid  of  manganese 
precipitate  and  also  the  excess  of  bromin  by  adding,  drop  by  drop,  the  clear  ferrous 
sulphate  solution.  Allow  the  solution  to  cool,  shaking  occasionally.  If  the  opera- 
tions have  been  properly  conducted,  a  heavy  white  precipitate  of  pentabromacetone 
is  obtained  which  becomes  crystalline  on  occasional  shaking  and  in  this  condition 
is  entirely  insoluble  in  water.  Allow  the  mixture  to  stand  overnight,  collect  it  by 
means  of  gentle  suction  on  a  tared  Gooch  crucible  provided  with  a  thin  pad  of  asbestos, 
previously  dried  over  sulphuric  acid  in  a  vacuum  desiccator,  wash  with  water  slightly 
acidified  with  sulphuric  acid  and  finally  wash  twice  with  water.  Dry  the  precipitate 
to  constant  weight  over  sulphuric  acid  in  a  vacuum  desiccator,  protecting  the  precipi- 
tate from  strong  light.  The  weight  of  pentabromacetone  multiplied  by  the  factor  0.424 
gives  the  equivalent  weight  of  anhydrous  citric  acid  (HsCeHjO?).  Occasionally  the 
pentabromacetone  is  first  obtained  in  the  form  of  oily  droplets.  These  become 
crystalline  on  standing  or  on  cooling  and  are  usually  discolored  by  negligible  traces 
of  manganese  or  iron. 

The  above  method  may  bo  applied  directly  to  the  sample  without  previous  pre- 
cipitation of  the  citric  acid  as  the  barium  salt  when  the  amount  of  sugar  or  other 
permanganate  reducing  substances  is  not  excessive.  In  this  case  begin  the  deter- 
mination with  the  addition  of  2  cc.  of  sulphuric  acid  (1  to  5)  and  the  treatment 
with  bromin  water. 

32  METALS.-TENTATIVE. 

Proceed  as  directed  under  XII. 


184  METHODS    OF   ANALYSIS 

33  PRESERVATIVES.-TENTATIVE. 
Proceed  as  directed  under  X. 

34  COLORING  MATTERS.-TENTATIVE. 
Proceed  as  directed  under  XI. 

35  SWEETENING  SUBSTITUTES.-TENTATIVE. 
Proceed  as  directed  under  X,  12,  36  or  37. 

BIBLIOGRAPHY. 

1  Chem.  Ztg.,  1895,  19:  552. 

"  Z.  angew.  Mikros.,  1896,  2:  260. 

"  Z.  Nahr.  Genussm.,  1911,  21:  185. 

*  J.  Assoc.  Official  Agri.  Chemists,  1915,  1:  480. 

6  Ibid.;  U.  S.  Bur.  Chem.  Bull.  162,  p.  65. 

6  Arch.  Chem.  Mikros.,  1914,  7:  285;  Abs.  Z.  Nahr.  Genussm.,  1915, 


XIV.     CANNED  VEGETABLES. 

1  PHYSICAL  EXAMINATIONS-TENTATIVE. 

Note  carefully  the  external  appearance  of  the  packages  to  detect  the  presence  of 
"leakers",  "swells"  or  "springers".  In  general  the  ends  of  sound  tins  of  canned 
vegetables  are  slightly  concave.  On  opening  the  package  note  the  relative  pro- 
portion of  solid  and  liquid  contents  and  the  level  of  the  solids  and  of  the  total  con- 
tents in  the  tin.  Note  the  general  appearance,  odor,  flavor,  color  and  size  of  the 
vegetables;  appearance  of  the  liquor  or  brine,  whether  clear  or  turbid,  and  the  con- 
dition of  the  inner  walls  of  the  container,  especially  as  to  blackening  and  corrosion. 
In  all  instances  the  analyst  should  familiarize  himself  with  the  normal  appearance, 
odor,  color,  flavor  and  other  properties  of  the  product  under  examination.  Care- 
ful macroscopic  or  microscopic  examination  should  be  made  for  worm  infestation, 
mold,  dirt,  or  other  evidence  of  decomposition  or  filth. 

2  PREPARATION  OF  SAMPLE.— TENTATIVE. 

The  preparation  of  the  sample  for  analysis  depends  upon  the  character  of  the 
product  and  the  determinations  to  be  made.  Samples  in  which  only  the  solid  or 
liquid  portion  is  required  should  be  treated  as  follows:  Weigh  the  full  can,  open, 
pour  off  the  liquid,  allow  the  solid  portion  to  drain  for  a  minute,  re-weigh  the  can 
and  drained  vegetables,  then  remove  the  solid  portion  and  weigh  the  dry,  empty 
can.  The  method  selected  for  draining  the  vegetables  is  dependent  upon  the  nature 
and  condition  of  the  sample.  In  most  cases  it  is  sufficient  to  cut  around  the  cover 
and  before  turning  it  back  allow  the  liquor  to  drain  through  the  slit.  Whenever  a 
portion  of  the  solid  material  would  escape  with  the  liquor  by  this  procedure,  drain 
upon  a  piece  of  cheese-cloth.  From  the  weights  thus  obtained  determine  the  per- 
centage of  liquid  and  solid  contents.  If  only  the  solid  portion  is  required,  separate 
in  a  similar  manner  and  grind  thoroughly  the  drained  vegetables  in  a  mortar  or 
food  chopper.  If  a  composite  of  the  solid  and  liquid  portion  is  required,  grind 
thoroughly  the  contents  of  the  can  in  a  mortar  or  food  chopper.  In  all  cases  mix 
thoroughly  the  portion  used  and  preserve  the  balance  in  glass-stoppered  containers. 
Unless  the  analysis  is  to  be  completed  in  a  reasonably  short  time,  determine  the 
moisture  in  a  portion  of  the  sample  prepared  as  above  and,  in  order  to  prevent  decom- 
position, dry  the  remainder  and  then  expose  to  air  until  it  becomes  air-dry,  grind,  mix 
thoroughly  and  preserve  in  glass-stoppered  containers.  A  second  moisture  determi- 
nation is  required  in  this  procedure. 

3  MOISTURE.-TENTATTVE. 

Dry  a  quantity  of  the  sample,  representing  about  2  grams  of  dry  material,  as 
directed  in  EX,  2. 

4  ASH.-OFFICIAL, 

Determine  total  ash  as  directed  in  VIII,  4. 

5  SALT.-OFFICIAL. 

Determine  chlorin  as  directed  under  HI,  1 5,  and  express  the  result  in  terms  of 
sodium  chlorid. 

185 


18G  METHODS    OF    ANALYSIS 

6  SUGARS.— TENTATIVE. 

Determine  reducing  sugars  and  sucrose  as  directed  in  VIII,  58  and  59,  varying 
the  weight  of  the  sample  employed  according  to  its  sugar  content. 

7  TOTAL  ACIDS.-TENTATIVE. 

Proceed  as  directed  in  XVI,  25.     Express  the  result  as  citric  acid;  1  cc.  of  N/10 
alkali  is  equivalent  to  0.0070  gram  of  crystallized  citric  acid. 

8  VOLATILE  ACIDS.-TENTATIVE. 

Proceed  as  directed  in  XVI,  27.     Express  the  results  as  acetic  acid;  1  cc.  of  N/10 
alkali  is  equivalent  to  0.0060  gram  of  acetic  acid. 

9  PRESERVATIVES.-TENTATIVE. 
Proceed  as  directed  under  X. 

10  COLORING  MATTERS.-TENTATFVE. 
Proceed  as  directed  under  XI. 

1 1  METALS.— TENTATIVE. 
Proceed  as  directed  under  XII. 

BIBLIOGRAPHY. 

1  U.  S.  Bur.  Chem.  Bulls.  125  and  151 ;  U.  S.  Dept.  Agr.  Bull.  196;  U.  S.  Bur.  Chem. 
Circ.  54;  Research  Laboratory,  National  Canners  Association,  Bull.  2. 


XV.     CEREAL  FOODS. 
WHEAT  FLOUR. 

1  MOISTURE.-OFFICIAL. 
Determine  moisture  as  directed  in  VIII,   2. 

2  ASH.-OFFICIAL. 

Determine  ash  as  directed  in  VIII,  4,  using  5  grams  of  the  flour. 

3  CRUDE  FAT   OR  ETHER  EXTRACT.-OFFICIAL. 

Determine  the  ether  extract  as  directed  in  VIII,  10.  With  fine  flour  the  addition 
of  an  equal  weight  of  clean,  dry  sand  is  frequently  necessary. 

4  CRUDE  FIBER.-OFFICIAL. 
Determine  crude  fiber  as  directed  in  VIII,  68. 

5  ACIDITY  OF  WATER  EXTRACT.— TENTATIVE. 

Weigh  18  grams  of  the  flour  into  a  500  cc.  Erlenmeyer  flask  and  add  200  cc.  of 
carbon  dioxid-free  water.  Place  the  flask,  loosely  stoppered,  for  an  hour  in  a  water 
bath  kept  at  40°C.,  shaking  occasionally.  Filter  upon  a  dry,  folded  filter,  return- 
ing the  first  10-15  cc.  of  the  filtrate  to  the  filter.  Titrate  100  cc.  of  the  clear  filtrate 
with  N/20  sodium  hydroxid,  using  phenolphthalein  as  an  indicator.  Each  cc.  of 
N/20  sodium  hydroxid  is  equivalent  to  0.05%  acidity  as  lactic  acid. 

6  SUGARS.-TENTATIVE. 

Determine  reducing  sugars  and  sucrose  as  directed  in  VIH,  58  and  59. 

7  PROTEIN.-OFFICIAL. 

Determine  nitrogen  as  directed  in  I,  18,  21  or  23.  Multiply  the  percentage  of 
nitrogen  by  5.7  to  obtain  the  percentage  of  protein. 

ALCOHOL-SOLUBLE  PROTEIN. 

8  Method  I.     {By  nitrogen  determination) — Tentative. 

Transfer  4  grams  of  the  flour  to  a  15O-200  cc.  bottle  or  Erlenmeyer  flask  and  add 
100  cc.  of  70%  alcohol  by  volume,  taking  care  that  none  of  the  material  sticks 
to  the  bottom  of  the  container.  Shake  thoroughly  10-12  times  at  intervals  of  30 
minutes  at  room  temperature,  or  shake  continuously  in  a  shaking  machine  for 
an  hour,  and  then  set  aside  overnight.  Shake  thoroughly  once  more,  allow  to  settle 
and  filter  through  a  drj^  folded  filter,  returning  the  first  runnings  to  the  filter  until 
a  clear  filtrate  is  obtained.  'Pipette  50  cc.  of  the  filtrate,  equivalent  to  2  grams  of 
the  sample,  into  a  Kjeldahl  flask,  dilute  with  100  cc.  of  water  to  prevent  frothing 
during  digestion  and  determine  nitrogen  as  directed  in  I,  18,  21  or  23. 

1S7 


188  METHODS    OF   ANALYSIS  [Chap. 

9  Method  II.     {By  Polarization) — Tentative. 

REAGENT. 

Millon's  reagent. — Dissolve  metallic  mercury  in  an  equal  weight  of  concentrated 
nitric  acid  and  dilute  the  solution  with  an  equal  volume  of  water.  The  freshly 
prepared  solution  must  be  used. 

1 0  DETERMINATION. 

Weigh  15.97  grams  of  the  flour  into  a  300  cc.  flask  and  add  100  cc.  of  alcohol  (sp. 
gr.  0.90).  Shake  at  30  minute  intervals  for  3  hours  and  then  let  stand  overnight. 
Filter  through  a  dry,  folded  filter  and  polarize  in  a  200  mm.  tube.  Precipitate  the 
proteins  in  50  cc.  of  the  filtrate  by  the  addition  of  5  cc.  of  Millon's  reagent.  Shake, 
filter  and  polarize  the  filtrate  in  a  200  mm.  tube.  Multiply  the  reading  in  degrees 
Ventzke  by  1.1  to  correct  for  the  dilution  and  deduct  the  product  from  the  first 
reading.     This  difference  multiplied  by  0.2  gives  the  per  cent  of  gliadin^  nitrogen. 

1 1  PROTEIN  SOLUBLE  IN  5  PER  CENT  POTASSIUM  SULPHATE  SOLUTION.— TENTATIVE. 

Weigh  6  grams  of  the  flour  into  a  200  cc.  flask  and  introduce  exactly  100  cc.  of 
5%  potassium  sulphate  solution.  Shake  at  30  minute  intervals  for  3  hours  and 
let  stand  overnight  or,  better  still,  agitate  at  moderate  speed  in  a  shaker  for  3  hours, 
let  settle  30  minutes,  filter  and  determine  the  nitrogen  in  50  cc.  of  the  filtrate  as 
directed  in  I,  18,  21  or  23. 

12  GLOBULIN  AND  ALBUMIN    (EDESTIN  AND  LEUCOSIN)  AND  AMINO    NITROGENS- 

TENTATIVE. 

Weigh  10  grams  of  the  flour  into  a  500  cc.  Erlenmeyer  flask,  add  250  cc.  of  1% 
sodium  chlorid  solution,  stopper  the  flask  and  shake  thoroughly.  Let  stand,  with 
occasional  shaking,  for  3  hours,  filter  through  dry  paper  and  evaporate  100  cc.  of 
the  filtrate  to  a  small  volume  in  a  Kjeldahl  digestion  flask  with  5  cc.  of  concentrated 
sulphuric  acid.  Add  the  remainder  of  the  sulphuric  acid  and  determine  the  nitro- 
gen as  directed  in  I,  18,  21  or  23.  To  a  second  100  cc.  of  the  filtrate  add  5  cc.  of  20% 
phosphotungstic  acid  solution,  shake  thoroughly,  allow  to  settle  and  filter  by  de- 
cantation.  Wash  slightly  with  water,  concentrate  the  filtrate  with  5  cc.  of  sul- 
phuric acid  in  a  Kjeldahl  flask  and  determine  the  nitrogen  (amino)  as  directed  in 
I,  18,  21  or  23.  Deduct  the  amino  nitrogen  from  the  nitrogen  found  in  the  first  frac- 
tion to  obtain  the  nitrogen  as  globulin  and  albumin'. 

■13  GLUTENIN.— TENTATIVE. 

Deduct  the  sum  of  the  potassium  sulphate-soluble  nitrogen,  1 1 ,  and  the  alcohol- 
soluble  nitrogen,  8,  from  the  total  nitrogen,  7,  and  multiply  the  difference  by  5.7. 

14  COLD  WATER-SOLUBLE  EXTRACT.— TENTATIVE. 

Weigh  20  grams  of  the  flour  into  a  500  cc.  Erlenmeyer  flask  and  add  gradually 
200  cc.  of  water  at  10°C.,  shake  vigorously  when  about  50  cc.  of  water  have  been 
added  and  continue  shaking  during  the  addition  of  the  remainder.  Allow  to  stand 
at  10°C.  for  40  minutes,  shaking  occasionally.  Filter  through  a  large,  dry,  coarse 
filter  paper,  returning  the  first  runnings  to  the  filter  until  a  clear  filtrate  is  obtained. 
Pipette  20  cc.  of  the  clear  filtrate  into  a  tared  dish,  evaporate  to  dryness  on  a  steam 
bath,  and  dry  to  constant  weight  in  an  oven  at  100°C.  for  periods  of  30  minutes. 


XV]  CEREAL   FOODS  189 

GLUTEN. 

15  Bamihl  Test.     (Qualitative) — Tentative. 

Place  a  very  small  quantity  (about  1.5  mg.)  of  the  flour  on  a  microscope  slide, 
add  a  drop  of  water,  containing  0.2  gram  of  water-soluble  eosin  in  1  liter,  and  mix 
by  means  of  a  cover-glass,  holding  the  latter  at  first  in  such  a  manner  that  it  is  raised 
slightly  above  the  slide,  and  taking  care  that  none  of  the  flour  escapes  from  beneath 
it.  Finally  allow  the  cover-glass  to  rest  on  the  slide  and  rub  it  back  and  forth 
until  the  gluten  has  collected  into  rolls.  The  operation  should  be  carried  out  on 
a  white  paper  so  that  the  formation  of  gluten  rolls  can  be  noted.  Wheat  flour,  or 
other  flours  containing  gluten,  show  by  this  treatment  a  copious  amount  of  gluten, 
which  absorbs  the  eosin  with  avidity,  assuming  a  carmine  color.  Rye  and  corn 
flour  yield  only  a  trace  of  gluten,  and  buckwheat  flour  no  appreciable  amount. 
The  preparations  are  best  examined  with  the  naked  eye,  thus  gaining  an  idea  of 
the  amount  of  gluten  present.  If  the  flour  is  coarse,  or  contains  a  considerable  amount 
of  bran  elements,  as  is  true  of  buckwheat  flour  and  low-grade  wheat  flour,  the  test 
should  be  made  after  bolting,  as  the  bran  particles  and  coarse  lumps  interfere  with 
the  formation  of  gluten  rolls. 

16  Quantitative  Method. — Tentative. 

Weigh  25  grams  of  the  flour  into  a  cup  or  porcelain  mortar,  add  sufficient  tap  water 
(about  15  cc.)  to  form  a  firm  dough  ball  and  work  into  a  dough  with  a  spatula  or 
pestle,  taking  care  that  none  of  the  material  adheres  to  the  utensil  employed.  Allow 
the  dough  to  stand  in  water  at  room  temperature  for  an  hour,  then  knead  gently 
in  a  stream  of  tap  water  until  the  starch  and  all  soluble  matters  are  removed.  This 
operation  requires  approximately  12  minutes  and  should  be  performed  over  bolting 
cloth  or  a  horsehair  sieve.  To  determine  if  the  gluten  is  starch-free  let  1  or  2  drops 
of  the  wash  water,  obtained  by  squeezing  the  gluten,  fall  into  a  beaker  containing 
perfectly  clear  water.  If  starch  is  present  a  cloudiness  appears.  Allow  the  gluten 
thus  obtained  to  stand  in  water  for  an  hour,  then  press  as  dry  as  possible  between 
the  hands,  roll  into  a  ball,  place  in  a  tared,  flat-bottomed  dish  and  weigh  as  moist 
gluten.  Transfer  to  an  oven,  dry  to  constant  weight  at  100°C.  (about  24  hours), 
cool  and  weigh  as  dry  gluten. 

CHLORIN. 

17  Qualitative   Test.     (Chlorin-Bleached  Flours) — Tentative. 

Extract  30  grams  of  the  flour  with  gasoline  and  allow  the  latter  to  evaporate. 
A  small  amount  of  oil  remains.  Heat  a  piece  of  copper  wire  in  a  colorless  gas  flame 
until  it  is  black  and  no  longer  colors  the  flame  green.  Dip  the  hot  end  of  the  wire 
into  the  oil  and  again  bring  into  the  flame.  If  chlorin  or  bromin  has  been  used  as 
a  bleaching  agent,  a  green  or  blue  coloration  is  produced. 

18  Quantitative  Method.     {Added  Chloriri  in  Chlorin-Bleached  Flours) — Tentative. 

Weigh  20  grams  of  the  flour  into  a  flat-bottomed  aluminium  dish,  8-10  cm.  in 
diameter,  and  dry  5  hours  in  a  boiling  water  or  steam  oven,  transfer,  with  as  little 
exposure  to  the  air  as  possible,  to  a  continuous  fat  extractor,  and  extract  for  16  hours 
with  anhydrous  alcohol-free  ether,  which  is  also  free  from  chlorin.  Transfer  the 
ether  extract  to  a  nickel  disl^  and  add  25  cc.  of  a  solution  containing  25  grams  of 
sodium  hydroxid  and  15  grams  of  sodium  nitrate  per  liter.  Place  the  dish  on  a 
steam  bath,  evaporate  to  dryness  and  ignite  in  a  muflSe   at  a  dull  red  heat  until 


190  METHODS    OF   ANALYSIS  [Chap. 

the  contents  are  thoroughly  charred.  Extract  the  charred  mass  with  25  cc.  of  1% 
nitric  acid  and  filter.  Return  the  residue  to  the  dish,  char  and  again  extract  with 
25  cc.  of  1%  nitric  acid,  filter,  wash  with  hot  water,  return  to  the  dish  and  ignite 
to  a  white  ash.  Dissolve  the  ash  in  5%  nitric  acid  and  add  the  solution  to  the  filtrates 
previously  obtained.  Determine  the  chlorin  in  the  combined  filtrates  either  gravi- 
metrically,  as  directed  in  I,  16  (a),  or  volumetrically,  as  directed  in  III,  15,  using 
N/50  solutions  for  greater  accuracy. 

NITRITE  NITROGEN.— TENTATIVE. 

19  REAGENTS. 

(a)  Sulphanilic  acid  solution. — Dissolve  0.5  gram  of  sulphanilic  acid  in  150  cc.  of 
20%  acetic  acid. 

(b)  Alpha-naphthylamin  hydrochlorid  solution. — Dissolve,  by  heating,  0.2  gram 
of  the  salt  in  150  cc.  of  20%  acetic  acid. 

(C)  Standard  nitrite  solution. — Dissolve  0.1097  gram  of  dry  C.  P.  silver  nitrite 
in  about  20  cc.  of  hot  water,  add  0.10  gram  of  C.  P.  sodivun  chlorid,  shake  until 
the  silver  chlorid  flocculates  and  make  up  to  1  liter.  Draw  off  10  cc.  of  the 
clear  solution  and  dilute  to  1  liter.  Each  cc.  of  the  last  solution  is  equivalent  to 
0.0001  mg.  of  nitrogen  as  nitrite.     [Cf.  IV,  12  (d)] 

The  silver  nitrite  may  be  prepared  as  follows :  To  a  cold  solution  of  about  2 
grams  of  sodium  or  potassium  nitrite  in  50  cc.  of  water,  add  a  solution  of  silver 
nitrate  as  long  as  a  precipitate  appears.  Decant  the  liquid  and  thoroughly  wash 
the  precipitate  with  cold  water.  Dissolve  in  boiling  water.  On  cooling  the  silver 
nitrite  crystallizes  out.  Dry  the  crystals  in  the  dark  at  ordinary  temperature  (pre- 
ferably in  a  vacuima). 

20  DETERMINATION. 

(1)  Select  a  series  of  100  cc.  volumetric  flasks  of  uniform  dimensions  and  color. 
Place  2  grams  of  high-grade,  nitrite-free  flour  in  each;  add  approximately  70  cc.  of 
nitrite-free  water  and  shake  until  the  flour  is  thoroughly  moistened.  Add  to  these 
flasks  varying  amounts  of  the  standard  sodium  nitrite  solution,  so  that  a  series  of 
comparison  standards  will  be  obtained  having  a  range  covering  the  probable  nitrite 
content  of  the  unknown  sample.  Reserve  1  flask  for  a  blank  test.  In  order  to 
avoid  making  a  large  series  of  standards  it  is  well  to  make  a  preliminary  test  to  as- 
certain the  approximate  nitrite  content  of  the  unknown.  Where  the  quantity  of 
nitrite  present  is  small,  the  nitrite  solution  in  the  flasks  may  be  increased  by  0.4 
cc.  each.  Where  bleaching  is  excessive,  1  gram  of  flour  may  be  used  throughout, 
or  the  standards  may  be  given  a  wider  variation  in  nitrite  content. 

To  each  of  2  similar  flasks  add  2  grams  of  the  flour  and  90  cc.  of  water;  shake 
thoroughly  and  digest  all  the  flasks,  including  the  blank,  in  a  water  bath  at  40°C. 
for  at  least  15  minutes;  add  2  cc.  each  of  the  sulphanilic  acid  and  alpha- 
naphthylamin  hydrochlorid  solutions  to  each  flask.  Continue  the  digestion  at 
40°C.  for  an  additional  20  minutes.  The  color  must  be  developed  in  all  the  flasks 
under  conditions  as  nearly  uniform  as  possible.  Make  up  to  the  marks  with  nitrite- 
free  water  and  compare  the  unknown  with  the  series  of  standards.  This  may  be 
done  in  a  large,  white,  enameled  pan;  the  effect  of  the  turbidity,  due  to  the  flour, 
being  minimized  by  the  white  background.  The  solutions  should  be  allowed  to 
subside  and  should  not  be  shaken  during  comparison;  or, 

(2)  Weigh  20  grams  of  the  flour  into  a  500  cc.  Erlenmeyer  flask,  add  200  cc.  of 
nitrite-free  water,  previously  warmed  to  40°C.,  and  close  the  flask  with  a  rubber 
stopper.     Shake  vigorouslj^  for  5  minutes  and  digest  for  an  hour  in  a  water  bath, 


XV]  CEREAL   FOODS  191 

keeping  the  temperature  of  the  liquid  in  the  flask  at  40°C.  and  shaking  at  10  minute 
intervals.  Finally  filter  on  a  dry,  nitrite-free,  folded  filter.  Return  the  first  run- 
nings to  the  filter  until  a  clear  filtrate  is  obtained.  Pipette  50  cc.  of  the  filtrate  and 
50  cc.  of  the  standard  nitrite  solution  into  small  flasks;  add  to  each,  50  cc.  of  water, 
2  cc.  each  of  the  sulphanilic  acid  and  alpha-naphthylamin  hydrochlorid  solutions, 
shake  and  allow  to  stand  an  hour  to  bring  out  the  color.  Compare  the  2  solutions 
in  a  colorimeter.  Divide  the  height  of  the  column  of  the  standard  solution  by  that 
of  the  solution  of  the  sample  to  obtain  the  parts  of  nitrogen  as  nitrous  acid  (free 
and  combined)  per  million  of  flour. 

21  GASOLINE  COLOR  VALUE.-TENTATIVE. 

Place  20  grams  of  the  flour  in  a  wide-mouthed,  glass-stoppered  120  cc.  bottle  and 
add  100  cc.  of  colorless  gasoline.  Stopper  tightly  and  shake  vigorously  for  5  minutes. 
After  standing  16  hours,  shake  again  for  a  few  seconds  until  the  flour  has  been  loos- 
ened from  the  bottom  of  the  bottle  and  thoroughly  mixed  with  the  gasoline,  then 
filter  immediately  on  a  dry  11  cm.  paper  into  an  Erlenmeyer  flask,  keeping  the  fun- 
nel covered  with  a  watch  glass  to  prevent  evaporation.  In  order  to  secure  a  clear 
filtrate,  a  certain  quantit}^  of  the  flour  should  be  allowed  to  pass  over  onto  the  paper 
and  the  first  portion  of  the  filtrate  passed  through  a  second  time.  It  will  be  found 
convenient  to  fit  the  filter  paper  to  the  funnel  by  means  of  water  and  dry  thoroughly 
either  by  standing  overnight  in  a  well-ventilated  place  or  by  heating. 

Determine  the  color  value  of  the  clear  gasoline  solution  in  a  Schreiner  or  similar 
colorimeter,  using  for  comparison  a  0.005%  potassium  chromate  solution.  This  solu- 
tion corresponds  to  a  gasoline  number  of  1.0  and  is  conveniently  prepared  by  dilu- 
ting 10  cc.  of  a  0.5%  solution  to  1  liter.  The  colorimeter  tube,  containing  the 
gasoline  solution,  should  first  be  adjusted  so  as  to  read  50  mm.,  then  the  tube 
containing  the  standard  chromate  solution  raised  or  lowered  until  the  shades  of  yellow 
in  both  tubes  match.  The  reading  of  the  chromate  solution,  divided  by  the  reading 
of  the  gasoline  solution,  gives  the  gasoline  color  value.  The  color  value  may  be  deter- 
mined also  in  Nessler  tubes,  using  for  comparison  potassium  chromate  solutions 
of  various  dilutions  prepared  from  a  0.5%  solution  and  filling  the  tubes  in  all  cases 
to  the  height  of  50  mm. 

BIBLIOGRAPHY. 

»  U.  S.  Bur.  Chem.  Bull.  152,  p.  104. 
*  Ibid.,  81,  p.  124. 
»  Ibid.,  122,  p.  54. 


XVI.    WINES. 

1  PHYSICAL  EXAMINATION.-TENTATIVE. 

Note  the  following:  whether  the  container  is  "bottle  full";  the  appearance  of 
the  wine,  whether  there  is  any  sediment  and  if  it  is  bright  or  turbid;  condition  when 
opened,  whether  still,  gaseous  or  carbonated;  color  and  depth  of  color;  odor,  whether 
vinous,  acetous,  pleasant  or  foreign;  and  taste,  whether  vinous,  acetous,  sweet, 
dry  or  foreign. 

2  PREPARATION   OF  SAMPLE.— TENTATIVE. 

If  gas  is  contained  in  the  wine,  remove  it  by  pouring  back  and  forth  in  beakers. 

Filter  the  wine,  regardless  of  appearance,  before  analysis  and  determine  immedi- 
ately the  specific  gravity  and  such  ingredients  as  alcohol,  acids  and  sugars  as  are 
liable  to  change  through  exposure. 

3  SPECIFIC  GRAVITY.-TENTATIVE. 

Determine  the  specific  gravity  at  -^s—^  by  means  of  a  pycnometer. 

4  ALCOHOL.— TENTATIVE. 

(a)  By  volume.— Measure  100  cc.  of  the  liquid  at  20°C.  into  a  300-500  cc.  distilla- 
tion flask,  add  50  cc.  of  water,  attach  the  flask  to  a  vertical  condenser  by  means  of 
a  bent  tube  and  distil  almost  100  cc,  making  up  to  100  cc.  volume  when  cooled 
to  20°C.  Foaming,  which  sometimes  occurs,  especially  with  young  wines,  may  be 
prevented  by  the  addition  of  a  small  amount  of  tannin.     To  determine  the  alcohol  in 

wines  which  have  undergone  acetous  fermentation  and  contain  an  abnormal  amount 
of  acetic  acid,  exactly  neutralize  the  portion  taken  with  sodium  hydro.xid  solution 
before  distilling.  This  is  unnecessary,  however,  in  wines  of  normal  taste  and  odor. 
Determine  the  specific  gravity  of  the  distillate  at  -p— ^  and  obtain  the  correspond- 
ing percentage  of  alcohol  by  volume  from  5. 

(b)  Grams  per  100  cc— From  the  specific  gravity  of  the  distillate,  obtained  in 
(a),  ascertain  from  5  the  corresponding  alcohol  content  in  grams  per  100  cc. 

(C)  By  weight. — Divide  the  number  of  grams  in  the  100  cc.  of  distillate,  as  ob- 
tained in  (b),  by  the  weight  of  the  sample  as  calculated  from  its  specific  gravity. 

(d)  By  immersion  refradometer.— The  percentages  of  alcohol,  as  determined  in 
(a)  and  (C),  may  be  verified  by  determining  the  immersion  refractometer  reading 
of  the  distillate  and  obtaining,  from  6,  the  corresponding  percentages  of  alcohol. 


193 


194 


METHODS    OF   ANALYSIS 


[Chap. 


Table  16.— Alcohol  Table. 

(Calculated  by  the  U.  S.  Bureau  of  Standards  from  its  experimental  results^) 

For  calculating  the  percentages  of  alcohol  in  mixtures  of  ethyl  alcohol  and  water  from  their 

specific  gravities. 


SPECIFIC 

ALCOHOL 

SPECIFIC 

ALCOHOL 

SPECIFIC 

ALCOHOL 

GRAVITY 

20°  0. 

Per  cent 

Per 

Grams 

ORAVITT 

20°  C. 

Per  cent 

Per 

Grams 

20°  C. 

Per  cent 

Per 

Grams 

4° 

by  volume 

cent  by 

per 

4° 

by  volume  cent  by 

per 

4° 

by  volume 

cent  by 

per 

at  20°  C. 

weight 

100  cc. 

at  20°  C. 

weight 

100  cc. 

at  20°  0. 

weight 

100  cc. 

0.99823 

0.00 

0.00 

0.00 

0.99492 

2  25 

1.79 

1.78 

0.99174 

4.50 

3.58 

3.55 

0.99815 

0.05 

0  OJf. 

0.04 

0.99485 

2  30 

1.82 

1.81 

0.99168 

4.55 

3.62 

3.59 

0.99808 

0.10 

0.08 

0.08 

0.99477 

2.35 

1.86 

1.85 

0.99161 

4.60 

3.66 

3.63 

0.99800 

0.15 

0.12 

0.12 

0.99470 

2.40 

1.90 

1.89 

0.99154 

4.65 

3.70 

3.67 

0.99793 

0  20 

0.16 

0.16 

0.99463 

2.45 

1.94 

1.93 

0.99147 

4.70 

3.74 

3.71 

0.99785 

0  25 

0.20 

0.20 

0.99456 

2  50 

1.98 

1.97 

0.99140 

4.75 

3.78 

3.75 

0.99778 

0  30 

0.21, 

0.24 

0.99449 

2.55 

2.02 

2.01 

0.99133 

4  80 

3.82 

3.79 

0.99770 

0  35 

0.28 

0.28 

0.99442 

2.60 

2.06 

2.05 

0.99127 

4.85 

3.86 

3.83 

0.99763 

0  40 

0.32 

0.32 

0.994.34 

2  65 

2.10 

2.09 

0.99120 

4.90 

3.90 

3.87 

0.99755 

0.45 

0.36 

0.36 

0.99427 

2.70 

2.14 

2.13 

0.99113 

4.95 

3.94 

3.91 

0.99748 

0.50 

0.40 

0.40 

0.99420 

2.75 

2.18 

2.17 

0.99106 

5.00 

3.98 

3.95 

0.99741 

0  55 

O.U 

0.44 

0.99413 

2.80 

2.22 

2.21 

0.99100 

5.05 

4.02 

3,99 

0.99734 

0.60 

0.47 

0.47 

0.99405 

2.85 

2.26 

2.25 

0.99093 

5  10 

4.06 

4.03 

0.99726 

0  65 

0.51 

0.51 

0.99398 

2  90 

2.30 

2.29 

0.99087 

5.15 

4.10 

4.07 

0.99719 

0.70 

0.55 

0.55 

0.99391 

2  95 

2.34 

2.33 

0.99080 

5.20 

4.14 

4.10 

0.99711 

0.75 

0.59 

0.59 

0.99384 

3  00 

2.38 

2.37 

0.99073 

5.25 

4.18 

4.14 

0.99704 

0.80 

0.6S 

0.63 

0.99.377 

3  05 

2.42 

2.41 

0.99066 

5  30 

4.22 

4.18 

0.99697 

0.85 

0.67 

0.67 

0.99.370 

3  10 

2.46 

2.45 

0.99060 

5.35 

4.26 

4.22 

0.99690 

0  90 

0.71 

0.71 

0.99.362 

3  15 

2.50 

2.49 

0.99053 

5.40 

4.30 

4.26 

0.99682 

0.95 

0.75 

0.75 

0.99355 

3.20 

2.54 

2.53 

0.99047 

5.45 

4.S4 

4.30 

0.99675 

1.00 

0.79 

0.79 

0.99.348 

3  25 

2.58 

2.57 

0.99040 

5.50 

4.38 

4.34 

0.99667 

1  05 

0.83 

0.83 

0.99341 

3  30 

2.62 

2.60 

0.99033 

5.56 

4-42 

4.38 

0.99660 

1.10 

0.87 

0.87 

0.99334 

3  35 

2.66 

2.64 

0.99026 

5  60 

4-46 

4.42 

0.99652 

1.15 

0.91 

0.91 

0.99327 

3  40 

2.70 

2.68 

0.99020 

5.65 

4.50 

4.46 

0.99645 

1.20 

0.95 

0.95 

0.99320 

3  45 

2.74 

2.72 

0.99013 

5.70 

4-54 

4.50 

0.99638 

1  25 

0.99 

0.99 

0.99313 

3  50 

2.78 

2.76 

0.99006 

5.75 

4.58 

4.54 

0.99631 

1  30 

1.03 

1.03 

0.99306 

3  55 

2.82 

2.80 

0.98999 

5.80 

4.62 

4.58 

0.99623 

1  35 

1.07 

1.07 

0.99299 

3  60 

2.86 

2.84 

0.98993 

5  85 

4.66 

4.62 

0.99616 

1  40 

1.11 

1.11 

0.99292 

3  65 

2.90 

2.88 

0.98986 

5.90 

4.70 

4.66 

0.99608 

1.45 

1.15 

1.15 

0.99285 

3.70 

2.94 

2.92 

0.98980 

5.95 

4.74 

4.70 

0.99601 

1.50 

1.19 

1.19 

0.99278 

3  75 

2.98 

2.96 

0.98973 

6  00 

4.78 

4.74 

0.99.594 

1.55 

1.23 

1.23 

0.99271 

3  80 

3.02 

3.00 

0.98967 

6  05 

4.82 

4.78 

0.99587 

1.60 

1.27 

1.26 

0.99264 

3.85 

3.06 

3.04 

0.98960 

6.10 

4.87 

4.82 

0.99579 

1  65 

1.31 

1.30 

0.99257 

3  90 

3.10 

3.08 

0.98954 

6.15 

4.91 

4.86 

0.99572 

1.70 

1.35 

1.34 

0.99250 

3  95 

3.14 

3.12 

0.98947 

6.20 

4.95 

4.89 

0.99564 

1  75 

1.39 

1.38 

0.99243 

4.00 

3.18 

3.16 

0.98941 

6.25 

4.99 

4.93 

0.99557 

1.80 

1.43 

1.42 

0.992.36 

4.05 

3.22 

3.20 

0.98934 

6  30 

5.03 

4.97 

0.99550 

1.85 

1-47 

1.46 

0.99229 

4.10 

3.26 

3.24 

0.98928 

6  35 

5.07 

5.01 

0.99543 

1  90 

l.r>l 

1.50 

0.99222 

4.15 

3.30 

3.28 

0.98921 

6.40 

5.11 

5.05 

0.99535 

1.95 

1.55 

1.54 

0.99215 

4.20 

3.34 

3.32 

0.98915 

6.45 

5.15 

5.09 

0.99528 

2.00 

1.59 

1.58 

0.99208 

4.25 

3.3S 

3.36 

0.98908 

6  50 

5.19 

5.13 

0.99520 

2  05 

1.63 

1.62 

0.99201 

4  30 

3.42 

3.39 

0.98902 

6.55 

5.23 

5.17 

0.99513 

2.10 

1.67 

1.66 

0.99195 

4.35 

3.46 

3.43 

0.98895 

6  60 

5.27 

5.21 

0.99.506 

2.15 

1.71 

1.70 

0.99188 

4.40 

3.50 

3.47 

0.98889 

6  65 

5.31 

5.25 

0.99499 

2.20 

1.75 

1.74 

0.99181 

4.45 

3.54 

3.51 

0.98882 

6.70 

5.35 

5.29 

XVI] 

WINES 

195 

! 

Table  16.— Alcohol  Table- 

-Continued. 

PECIFIC 

ALCOHOL 

SPECIFIC 

ALCOH'JL 

SPECIFIC 

ALCOHOL 

RAVITY 

20°  C. 

Per  cent 

Per 

Grama 

°Iqo^^ 

Per  cent 

Per 

Grams 

GR.WITY 

20°  C. 

Per  cent 

Per 

Grams 

4° 

by  volume 

cent  by 

per 

4° 

by  volume 

cent  by 

per 

4° 

by  volume 

cent  by 

per 

at  20°  C. 

weight 

100  cc. 

at  20°  C. 

weight 

100  cc. 

at  20°  C. 

weight 

100  cc. 

1.98876 

6  75 

5.S9 

5.33 

0.98566 

9  25 

7.41 

7.30 

0.98267 

11.76 

9.44      9.28 

198870 

6  80 

5.4S 

5.37 

0.98560 

9  30 

7.45 

7.34 

0.98261 

11.80 

9.48      9.31 

:.9SS64 

6  85 

547 

5.41 

0.98554 

935 

7.49 

7.38 

0.98255 

11.86 

9.52      9.35 

9S857 

6  90 

5.51 

5.45 

0.98549 

9  40 

7.53 

7.42 

0.98250 

11.90 

9.56      9.39 

OSS.jI 

6  95 

5.55 

5.49 

0.98543 

9  45 

7.57 

7.46 

0.98244 

11  95 

9.60      9.43 

assK") 

7  00 

5.59 

5.53 

0.98537 

9.50 

7.61 

7.50 

0.98238 

12  00 

9.64      9.47 

<tss3<.) 

7.05 

5.63 

5.57 

0.98531 

9.55 

7.65 

7.54 

0.98232 

12  05 

9.68      9.51 

()ss:;2 

7  10 

5.67 

5.60 

0.98524 

9  60 

7.69 

7.58 

0.98226 

12.10 

9.72      9.55 

!»SS26 

7.15 

5.71 

5.64 

0.98518 

9.65 

7.73 

7.62 

0.98220 

12.15 

9.76      9.59 

()VSJ() 

7.20 

5.75 

5.68 

0.98512 

9.70 

7.77 

7.66 

0.98214 

12  20 

9.80      9.63 

OSS  13 

7  25 

5.79 

5.72 

0.98506 

9.75 

7.81 

7.70 

0.98208 

12  25 

9.84      9.67 

98,^06 

7  30 

5.83 

5.76 

0.98501 

9.80 

7.85 

7.73 

0.98203 

12.30 

9.89      9.71 

98800 

7  35 

5.87 

5.80 

0.98495 

9.85 

7.89 

7.77 

0.98197 

12  35 

9.93      9  75 

OSTOt 

7  40 

5.91 

5.84 

0.98488 

9.90 

7.93 

7.81 

0.98191 

12  40 

9.97      9.79 

!"S7\S 

7.45 

5.95 

5.88 

0.98482 

9.96 

7.97 

7.85 

0.98185 

12  46 

10.01      9.83 

flS7Sl 

7  50 

5.99 

5.92 

0.98476 

10  00 

8.02 

7.89 

0.98180 

12.50 

10.05      9.87 

■98775 

7  55 

6.03 

5.96 

0.98470 

10.05 

8.06 

7.93 

0.98174 

12  55 

10.09      9.91 

98769 

7  60 

6.07 

6.00 

0.98463 

10.10 

8.10 

7.97 

0.98168 

12  60 

10.13      9.95 

!>S7f;3 

7  65 

6.11 

6.04 

0.98457 

10.15 

8.14 

8.01 

0.98162 

12.65 

10.17      9.99 

!'S7r)G 

7  70 

6.15 

6.08 

0.98452 

10.20 

8.18 

8.05 

0.98156 

12  70 

10.21     10.03 

9S750 

7  75 

6.19 

6.12 

0.98446 

10.25 

8.22 

8.09 

0.98150 

12.75 

10.25    10.07 

98744 

7  80 

6.U 

6.16 

0.98441 

10.30 

8.26 

8.13 

0.98145 

12  80 

10.29     10  10 

98738 

7.85 

6.28 

6.20 

0.98435 

10  35 

8.30 

8.17 

0.98139 

12  86 

10.33     10.14 

'K731 

7  90 

6.32 

6.24 

0.98428 

10  40 

8.34 

8.21 

0.98132 

12  90 

10.38     10.18 

MS7_'.') 

7  95 

6.36 

6.28 

0.98422 

10.45 

8.38 

8.25 

0.98127 

12  96 

10.42    10.22 

198718 

8  00 

6.40 

6.32 

0.98416 

10.50 

8.42 

8.29 

0.98122 

13  00 

10.46     10.26 

98712 

8  05 

6.44 

6.36 

0.98410 

10.55 

8.46 

8.33 

0.98116 

13  05 

10.50    10.30 

'98700 

8  10 

6.48 

6.39 

0.98404 

10  60 

8.50 

8.37 

0.98111 

13  10 

10.54     10.34 

'98700 

8  15 

6.52 

6.43 

0.98398 

10.66 

8.64 

8.41 

0.98105 

13  15 

10.58    10.38 

'98694 

8  20 

6.56 

6.47 

0.98391 

10.70 

8.58 

8.45 

0.98100 

13  20 

10.62     10.42 

'.ISIiSS 

8  25 

6.60 

6.51 

0.98385 

10.75 

8.62 

8.49 

0.98094 

13  25 

10.66     10.46 

9StiS'J 

8  30 

6.64 

6.55 

0.98379 

10.80 

8.66 

8.52 

0.98089 

13  30 

10.70     10.50 

'9S676 

8  35 

6.68 

6.59 

0.98373 

10  85 

8.70 

8.56 

0.98083 

13  35 

10.74     10.54 

''98670 

8  40 

6.72 

6.63 

0.98368 

10.90 

8.75 

8.60 

0.98077 

13  40 

10.78     10  58 

'98664 

8  45 

6.76 

6.67 

0.98362 

10.95 

8.79 

8.64 

0.98071 

13  45 

10.82    10.62 

i9Sr,,-)S 

8  50 

6.80 

6.71 

0.98356 

11.00 

8.83 

8.68 

0.98066 

13  50 

10.86    10.66 

i9Sti.">'J 

8  55 

6.84 

6.75 

0.98350 

11.06 

8.87 

8.72 

0.98060 

13  56 

10.90    10.70 

t9864t> 

8  60 

6.88 

6.79 

0.98344 

11.10 

8.91 

8.76 

0.98054 

13  60 

10.95     10.74 

198640 

8  65 

6.92 

6.83 

0.98338 

11.16 

8.95 

8.80 

0.98048 

13  66 

10.99     10.78 

i;98G33 

8  70 

6.96 

6.87 

0.98332 

11.20 

8.99 

8.84 

0.98043 

13  70 

11.03     10.81 

^98627 

8  75 

7.00 

6.91 

0.98326 

11  26 

9.03 

8.88 

0.98037 

13  76 

11.07    10.85 

08620 

8  80 

7.04 

6.95 

0.98320 

W  30 

9.07 

8.92 

0.98031 

13  80 

//./;     10.89 

(198614 

8  85 

7.08 

6.99 

0.98314 

11.36 

9.11 

8.96 

0.98025 

13  85 

11.15    10.93 

l|9S60S 

8  90 

7.12 

7.03 

0.98308 

11.40 

9.15 

9.00 

0.9S020 

13  90 

11.19     10.97 

(98602 

8  95 

7.16 

7.07 

0.98302 

11.46 

9.19 

9.04 

0.98014 

13  95 

11.23    11.01 

('98596 

9  00 

7.20 

7.10 

0.98296 

11  60 

9.23 

9.08 

0.98009 

14  00 

11.28     11.05 

(9S590 

9  05 

7.24 

7.14 

0.98290 

11.65 

9.27 

9.12 

0.98003 

14  05 

11.32     11.09 

()SnS4 

9  10 

7.29 

7.18 

0.98285 

11.60 

9.32 

9.16 

0.97998 

14  10 

11.36     11.13 

ns.-,7S 

9  15 

7.33 

7  22 

0.98279 

11.66 

9.36 

9.20 

0.97992 

14.15 

11.40     11.17 

"'_ 

9  20 

7.37 

7^26 

0.98273 

11.70 

9.40 

9.24 

0.97986 

14.20 

11. U     11.21 

196 


METHODS    OF   ANALYSIS 


[Chap. 


5 

Table  16.— Alcohol  Table.- 

-Continued. 

ALCOHOL 

ALCOHOL 

ALCOHOL 

SPECIFIC 

SPECIFIC 

SPECIFIC 

GRAVITY 
20°  C. 

Per  cent 

Per 

Grama 

°Iqo^^ 

Per  cent 

Per 

Grams 

°2(r'^a^ 

Per  cent 

Per 

Grai 

4° 

by  volume 

cent  by 

per 

4° 

by  volume 

cent  by 

per 

4° 

by  volume 

cent  by 

pe 

at  20°  C. 

weight 

100  cc. 

at  20°  C. 

weight 

100  cc. 

at  20°  C. 

weight 

100 

0.97980 

14  25 

11.48 

11.25 

0.97704 

16.75 

13.53 

13.22 

0.97438 

19  26 

15.59 

15. 

0.97975 

14.30 

11.52 

11.29 

0.97699 

16  80 

13.57 

13.26 

0.97433 

19  30 

15.64 

15. 

0.97969 

14  35 

11.56 

11.33 

0.97694 

16.85 

13.61 

13.30 

0.97428 

19  35 

15.68 

15. 

0.97964 

14  40 

11.60 

11.37 

0.97689 

16.90 

13.66 

13.34 

0.97423 

19  40 

15.72 

15. 

0.97958 

14  45 

11.64 

11.41 

0.97683 

16  95 

13.70 

13.38 

0.97417 

19.45 

15.76 

15. 

0.97953 

14.50 

11.68 

11.44 

0.97678 

17  00 

13.74 

13.42 

0.97412 

19  50 

15.80 

15. 

0.97947 

14.55 

11.72 

11.48 

0.97672 

17.05 

13.78 

13.46 

0.97407 

19.55 

15.84 

15. 

0,97942 

14  60 

11.77 

11.52 

0.97667 

17.10 

13.82 

13.50 

0.97402 

19.60 

15.88 

15. 

0.97936 

14  65 

11.81 

11.56 

0.97661 

17  15 

13.86 

13.54 

0.97396 

19.65 

15.92 

15. 

0.97930 

14.70 

11.85 

11.60 

0.97656 

17.20 

13.90 

13.58 

0.97391 

19.70 

15.97 

15. 

0.97924 

14.75 

11.89 

11.64 

0.97650 

17.25 

13.94 

13.62 

0.97386 

19.75 

16.01 

15. 

0.97919 

14  80 

11.93 

11.68 

0.97645 

17  30 

13.98 

13.66 

0.97381 

19.80 

16.05 

15. 

0.97913 

14  85 

11.97 

11.72 

0.97639 

17  35 

14-02 

13.70 

0.97375 

19  85 

16.09 

15. 

0.97908 

14  90 

12.01 

11.76 

0.97634 

17.40 

14-07 

13.74 

0.97370 

19.90 

16.13 

15.' 

0.97902 

14.95 

12.05 

11.80 

0.97629 

17.45 

14-11 

13.78 

0.97364 

19  95 

16.17 

15.' 

0.97897 

15  00 

12.09 

11.84 

0.97624 

17.50 

14-15 

13.81 

0.97359 

20  00 

16.21 

15.' 

0.97891 

15  05 

12.13 

11.88 

0.97618 

17.55 

14-19 

13.85 

0.97354 

20.05 

16.25 

15. { 

0.97885 

15.10 

12.18 

11.92 

0.97613 

17.60 

14-23 

13.89 

0.97349 

20.10 

16.30 

15. J 

0.97879 

15  15 

12.22 

11.96 

0.97607 

17.65 

14-27 

13.93 

0.97344 

20.15 

16.34 

15. < 

0.97874 

15  20 

12.26 

12.00 

0.97602 

17.70 

14-31 

13.97 

0.97339 

20.20 

16.38 

15. < 

0.97868 

15  25 

12.30 

12.04 

0.97596 

17.75 

14-35 

14.01 

0.97333 

20  26 

16.42 

15.< 

0.97863 

15  30 

12.34 

12.08 

0.97591 

17.80 

14-40 

14.05 

0.97328 

20.30 

16.46 

16.( 

0.97857 

15  35 

12.38 

12.12 

0.97586 

17.85 

14-44 

14.09 

0.97322 

20  35 

16.50 

16.( 

0.97852 

15  40 

12.42 

12.16 

0.97581 

17  90 

U-48 

14.13 

0.97317 

20.40 

16.55 

16. 

0.97846 

15  45 

12.46 

12.20 

0.97575 

17  95 

14.52 

14.17 

0.97311 

20.45 

16.59 

16. 

0.97841 

15  50 

12.50 

12.23 

0.97570 

18  00 

14-56 

14.21 

0.97306 

20  50 

16.63 

16. 

0.97835 

15  55 

12.54 

12.27 

0.97564 

18.05 

14-60 

14.25 

0.97300 

20.55 

16.67 

16.i 

0.97830 

15  60 

12.59 

12.31 

0.97559 

18.10 

14-64 

14.29 

0.97295 

20  60 

16.71 

16.5 

0.97824 

15  65 

12.63 

12.35 

0.97553 

18.15 

14-68 

14.33 

0.97289 

20  65 

16.75 

16.; 

0.97819 

15.70 

12.67 

12.39 

0.97548 

18  20 

14-73 

14.37 

0.97284 

20.70 

16.80 

16.; 

0.97813 

15  75 

12.71 

12.43 

0.97542 

18  25 

14-77 

14.41 

0.97278 

20  76 

16.84 

16.; 

0.97808 

15  80 

12.75 

12.47 

0.97538 

18  30 

14-81 

14.45 

0.97273 

20  80 

16.88 

16.^ 

0.97802 

15  85 

12.79 

12.51 

0.97532 

18.35 

14-85 

14.49 

0.97268 

20  85 

16.92 

16.^ 

0.97797 

15  90 

12.83 

12.55 

0.97527 

18.40 

14-89 

14.52 

0.97263 

20  90 

16.96 

16.. 

0.97791 

15  95 

12.87 

12.59 

0.97522 

18  45 

14-93 

14.56 

0.97257 

20  95 

17.00 

16.. 

0.97786 

16  00 

12.92 

12.63 

0.97517 

18.50 

14-97 

14.60 

0.97252 

21.00 

17.04 

16.. 

0.97780 

16  05 

12.96 

12.67 

0.97512 

18  55 

15.01 

14.64 

0.97247 

21.05 

17.08 

16. ( 

0.97775 

16  10 

13.00 

12.71 

0.97507 

18  60 

15.06 

14.68 

0.97242 

21.10 

17.13 

16. 

0.97769 

16  15 

13.04 

12.75 

0.97501 

18  65 

15.10 

14.72 

0.97237 

21  15 

17.17 

16.' 

0.97764 

16  20 

13.08 

12.79 

0.97496 

18  70 

15.14 

14.76 

0.97232 

21  20 

17.21 

16. 

0.97758 

16.25 

13.12 

12.83 

0.97490 

18.75 

15.18 

14.80 

0.97227 

21  25 

17.25 

16. 

0.97753 

16  30 

13.16 

12.87 

0.97485 

18.80 

15.22 

14.84 

0.97222 

21  30 

17.29 

16.{ 

0.97747 

16  35 

13.20 

12.91 

0.97479 

18  85 

15.26 

14.88 

0.97216 

21  35 

17.33 

16. { 

0.97742 

16.40 

13.24 

12.95 

0.97474 

18.90 

15.30 

14.92 

0.97210 

21.40 

17.38 

16.{ 

0.97737 

16.45 

13.28 

12.99 

0.97469 

18  95 

15.34 

14.96 

0.97204 

21.45 

17.42 

16. 

0.97732 

16  50 

13.33 

13.02 

0.97464 

19.00 

15.39 

15.00 

0.97199 

21.50 

17.46 

16. 

0.97726 

16  55 

13.37 

13.06 

0.97459 

19  05 

15.43 

15.04 

0.97193 

21.55 

17.50 

17. 

0.97721 

16  60 

13.41 

13.10 

0.97454 

19  10 

15.47 

15.08 

0.97188 

21  60 

17.54 

17. 

0.97715 

16  65 

13.45 

13.14 

0.97449 

19.15 

15.51 

15.12 

0.97183 

21  65 

17.58 

17. 

0.97710 

16  70 

13.49 

13.18 

0.97444 

19  20 

15.55 

15.16 

0.97178 

21.70 

17.63 

17. 

XVI] 


WINES 


197 


Table  16.— Alcohol  Table.— Continued. 


,  „..„. 

.\LCOHOL 

SPECIFIC 

ALCOHOL 

SPECIFIC 

ALCOHOL 

Per  cent 

Per 

Grams 

GRAVITY 

20°  C. 

Per  rent 

Per 

Grams 

GR.WITY 

20°  C. 

Per  cent 

Per 

Gram* 

by  volume 

cent  by 

per 

4° 

by  volume 

cent  by 

per 

4° 

by  volume 

cent  by 

per 

at  20°  C. 

weight 

100  cc. 

at  20°  C. 

weight 

100  cc. 

at  20°  C. 

weight 

100  cc. 

7172 

21  75 

17.67 

17.17 

0.96896 

24.25 

19.75 

19.14 

0.96612 

26.76 

21.85 

21.12 

21  80 

17.71 

17,21 

0.96801 

24  30 

19.80 

19.18 

0.96606 

26  80 

21.90 

21.16 

21  85 

17.75 

17.25 

0.96885 

24  35 

19.84 

19.22 

0.96600 

26  85 

21.94 

21.20 

21  90 

17.79 

17.29 

0.96880 

24  40 

19.88 

19.26 

0.06505 

26  90 

21.98 

21.23 

;71o0 

21  95 

17.83 

17.33 

0.96874 

24  45 

19.92 

19.30 

0.96589 

26  96 

22.02 

21.27 

71 4o 

22  00 

17.88 

17.37 

0.96869 

24  50 

19.96 

19.34 

0.96583 

27  00 

22.07 

21.31 

7i:;'i 

22  05 

17.92 

17.41 

0.9&S63 

24  55 

20.00 

19.38 

0.06577 

27  05 

22.11 

21.35 

nil 

22  10 

17.96 

17.45 

0.96.S57 

24  60 

20.05 

19.42 

0.06571 

27  10 

22.15 

21.39 

22  15 

18.00 

17.49 

0.90851 

24  65 

20.09 

19.46 

0.06505 

27  16 

22.19 

21.43 

71 L':! 

22  20 

18.04 

17.52 

0.96846 

24  70 

20.13 

19.50 

0.06559 

27  20 

22.24 

21.47 

,711S 

22  25 

18.08 

17.56 

0.96840 

24  75 

20.17 

19.54 

0.96553 

27  26 

22.28 

21.51 

!7li:^ 

22  30 

18.13 

17.60 

0.96.S35 

24  80 

20.22 

19.58 

0.06548 

27  30 

22.32 

21.55 

17107 

22  35 

18.17 

17.64 

0.96820 

24  86 

20.26 

19.62 

0.96542 

27  36 

22.36 

21.59 

7102 

22  40 

18.21 

17.68 

0.96823 

24  90 

20.30 

19.66 

0.96536 

27  40 

22.40 

21.63 

7006 

22  45 

18.25 

17.72 

0.96817 

24  95 

20.34 

19.70 

0.96530 

27  45 

22.44 

21.67 

7001 

22  50 

18.29 

17.76 

0.96812 

25  00 

20.38 

19.73 

0.96525 

27  50 

22.49 

21.71 

70^5 

22  55 

18.33 

17.80 

0.96806 

26  05 

20.42 

19.77 

0.96519 

27  56 

22.53 

21.75 

7lK0 

22  60 

18.38 

17.84 

0.96801 

25  10 

20.47 

19.81 

0.96513 

27  60 

22.57 

21.79 

-     -  ; 

22  65 

18.42 

17.88 

0.96795 

25  15 

20.51 

19.85 

0.96.507 

27.66 

22.61 

21.83 

' 

22  70 

18.46 

17.92 

0.96789 

25.20 

20.55 

19.89 

0.96501 

27.70 

22.66 

21.87 

706.S 

22  75 

18.50 

17.96 

0.96783 

26  25 

20.59 

19.93 

0.96495 

27.76 

22.70 

21.91 

70."i.^ 

22  80 

18.54 

18.00 

0.96778 

25  30 

20.64 

19.97 

0.964,S9 

27  80 

22.74 

21.94 

70.-i2 

22  85 

18.58 

18.04 

0.96772 

25  35 

20.68 

20.01 

0.06483 

27  85 

22.78 

21.98 

7047 

22  90 

18.63 

18.08 

0.96766 

25  40 

20.72 

20.05 

0.96477 

27  90 

22.83 

22.02 

7011 

22  95 

18.67 

18.12 

0.96760 

26.46 

20.76 

20.09 

0.96471 

27  95 

22.87 

22.06 

23  00 

18.71 

18.16 

0.96755 

25  60 

20.80 

20.13 

0.96465 

28  00 

22.91 

22.10 

,M 

23  05 

18.75 

18.20 

0.96749 

26  65 

20.84 

20.17 

0.96459 

28  05 

22.95 

22.14 

7()j:) 

23  10 

18.79 

18.24 

0.96744 

25  60 

20.89 

20.21 

0.96454 

28  10 

23.00 

22.18 

7010 

23  15 

18.83 

18.28 

0.96738 

25  66 

20.93 

20.25 

0.9644S 

28  15 

23.04 

22  22 

701  :i 

23  20 

18.88 

18.31 

0.96733 

25  70 

20.97 

20.29 

0.96442 

28  20 

23.08 

22^26 

23  25 

18.92 

18.35 

0.96727 

25  76 

21.01 

20.33 

0.96436 

28.25 

23.12 

22.30 

23  30 

18.96 

18.39 

0.96722 

26  80 

21.06 

20.37 

0.96430 

28  30 

23.17 

22.34 

23  35 

19.00 

18.43 

0.96716 

26  85 

21.10 

20.41 

0.96424 

28  35 

23.21 

22.38 

./111 

23  40 

19.04 

18.47 

0.96710 

26  90 

21.14 

20.44 

0.96418 

28  40 

23.25 

22  42 

23  45 

19.08 

18.51 

0.96704 

26  96 

21.18 

20.48 

0.96412 

28.45 

23.29 

22^46 

1 

23  50 

19.13 

18.55 

0.96699 

26  00 

21.22 

20.52 

0.96406 

28  50 

23.33 

22.50 

1 

23  55 

19.17 

18.59 

0.96693 

26  05 

21.26 

20.56 

0.96400 

28  56 

23.37 

22.54 

1 

23  60 

19.21 

18.63 

0.96687 

26  10 

21.31 

20.60 

0.96393 

28  60 

23.42 

22.57 

23  65 

19.25 

18.67 

0.96681 

26  15 

21.35 

20.64 

0.96387 

28  65 

23.46 

22.61 

1  605S 

23  70 

19.29 

18.71 

0.96675 

26  20 

21.39 

20.68 

0.96381 

28  70 

23.51 

22.65 

)  6052 

23  75 

19.33 

18.75 

0.96669 

26  26 

21.4S 

20.72 

0.96375 

28  76 

23.55 

22.69 

)6947 

23  80 

19.38 

18.79 

0.96664 

26  30 

21.48 

20.76 

0.96369 

28  80 

23.59 

22.73 

)6941 

23  85 

19.42 

18.83 

0  96658 

26  35 

21.52 

20.80 

0.96363 

28  85 

23.63 

22.77 

)  6936 

23  90 

19.46 

18.87 

0.96653 

26  40 

21.56 

20.84 

0.96357 

28  90 

23.67 

22.81 

3  6930 

23  95 

19.50 

18.91 

0.96647 

26  45 

21.60 

20.88 

0.96351 

28  96 

23.71 

22.85 

Vr,OL\-, 

24  00 

19.55 

18.94 

0.96641 

26  50 

21.64 

20.92 

0.90346 

29  00 

23.76 

22.89 

24  05 

19.59 

18.08 

0.96635 

26  56 

21.68 

20.96 

0.96340 

29  05 

23.80 

22.93 

24  10 

19.63 

19.02 

0.96680 

26.60 

81.73 

21.00 

0  96334 

29  10 

23.84 

22.97 

7 

24  15 

19.67 

19.06 

0.96624 

26  65 

21.77 

21.04 

0  9632S 

29.15 

23.88 

23.01 

24  20 

19.71 

19.10 

0.96618 

26  70 

21.81 

21.  OS 

0.96322 

29  20 

23.93 

23.05 

198 


METHODS    OF   ANALYSIS 


[Chap. 


5 

Table  16.— Alcohol  Table.- 

—Continued. 

SPECIFIC 

.VLCOHOL 

SPECIFIC 

ALCOHOL 

SPECIFIC 

ALCOHOL 

GRAVITY 
20°  C. 

Per  cent 

Per 

Grams 

"20^"^ 

Per  cent 

Per 

Grams 

26°  C. 

Per  cent 

Per 

Gra 

-40 

by  volume 

cent  by 

per 

4° 

by  volume 

cent  by 

per 

4° 

by  volume 

cent  by 

P« 

at  20°  C. 

weight 

100  cc. 

at  20°  C. 

weight 

100  cc. 

at  20°  C. 

weight 

100 

0.96316 

29.25 

23.97 

23.09 

0.96005 

31.76 

26.10 

25.06 

0.95669 

34.26 

28.26 

27 

0.96310 

29  30 

24  01 

23.13 

0.95998 

31.80 

26.15 

25.10 

0.95662 

34.30 

28.30 

27 

0 . 96304 

29  35 

24.05 

23.17 

0.95992 

31.86 

26.19 

25.14 

0.95655 

34.35 

28.34 

27 

0  96297 

29  40 

24.10 

23.21 

0.95985 

31  90 

26.23 

25.18 

0.95648 

34  40 

28.39 

27 

0.96291 

29.45 

24 -U 

23.25 

0.95979 

31.95 

26.27 

25.22 

0.95641 

34  46 

28.43 

27 

0.96285 

29  50 

24.1s 

23.29 

0.95972 

32  00 

26.32 

25.26 

0.95634 

34.50 

28.48 

27 

0 . 96279 

29  55 

24-22 

23.33 

0.95965 

32  05 

26.36 

25.30 

0.95627 

34.65 

28.52 

27 

0  96273 

29  60 

24.27 

23.36 

0.95958 

32  10 

26.41 

25.34 

0.95619 

34  60 

28.56 

27 

0.96267 

29  65 

24.31 

23.40 

0.95952 

32  15 

26.45 

25.38 

0.95612 

34.65 

28.60 

27 

0.96261 

29.70 

24.35 

23.44 

0.95945 

32  20 

26.49 

25.42 

0.95605 

34.70 

28.65 

27 

0.96255 

29  76 

24.39 

23.48 

0.95939 

32  26 

26.53 

25.46 

0.95598 

34.76 

28.69 

27 

0.96248 

29  80 

2  A.  44 

23.52 

0.95932 

32  30 

26.58 

25.50 

0.95591 

34  80 

28.74 

27 

0.96242 

29  85 

24.48 

23.56 

0.95926 

32.35 

26.62 

25.54 

0.95584 

34  85 

28.78 

27 

0.96236 

29  90 

24.52 

23.60 

0.95920 

32.40 

26.66 

25.58 

0.95577 

34  90 

28.82 

27 

0.96230 

29.95 

24.56 

23.64 

9.95913 

32.46 

26.70 

25.61 

0.95570 

34.95 

28.86 

27 

0 . 96224 

30  CO 

24. 61 

23.68 

0.95906 

32.50 

26.75 

25.64 

0.95563 

36  00 

28.91 

27 

0  96218 

30  05 

24.65 

23.72 

9.95900 

32.55 

26.79 

25.68 

0.95556 

35  05 

28.95 

27 

0.96211 

30  10 

24.69 

23.76 

0.95893 

32  60 

26.83 

25.72 

0.95549 

35.10 

29.00 

27 

0.96205 

30  15 

24.73 

23.80 

0.95887 

32  65 

26.87 

25.76 

0.95542 

35.16 

29.04 

27 

0.96199 

30.20 

24.78 

23.84 

0.95880 

32.70 

26.92 

25.80 

0.95535 

36.20 

29.08 

27 

0.96193 

30  25 

24.82 

23.88 

0.95873 

32.75 

26.96 

25.84 

0.95528 

36  25 

29.12 

27 

0.96187 

30  30 

24.87 

23.92 

0.95866 

32.80 

27.01 

25.89 

0.95521 

35.30 

29.17 

27 

0.96181 

30  35 

24.91 

23.96 

0.95859 

32.85 

27.05 

25.93 

0.95513 

36  35 

29.21 

27 

0.96175 

30  40 

24.95 

24.00 

0.95852 

32  90 

27.09 

25.97 

0.95506 

35.40 

29.26 

27 

0.96169 

30.45 

24.99 

24.04 

0.95846 

32  96 

27.13 

26.01 

0.95499 

35.45 

29.30 

27 

0.96163 

30  50 

25.04 

24.08 

0.95839 

33.00 

27.18 

26.05 

0.95492 

35.60 

29.34 

28 

0.96157 

30  55 

25.08 

24.12 

0.95833 

33.06 

27.22 

26.09 

0.95485 

35  56 

29.38 

28 

0  96150 

30.60 

25.12 

24.15 

0.95826 

33  10 

27.27 

26.13 

0  95478 

35  60 

29.43 

28 

0.96141 

30  65 

25.16 

24.19 

0.95819 

33  16 

27.31 

26.17 

0.95470 

35  65 

29.47 

28 

0.96138 

30.70 

25.21 

24.23 

0.95812 

33  20 

27.35 

26.21 

0.95463 

35.70 

29.52 

28 

0.96132 

30.75 

25.25 

24.27 

0.95806 

33  25 

27.39 

26.25 

0.95456 

35.76 

29.56 

28 

0.96125 

30  80 

25.30 

24.31 

0.95799 

33  30 

27.44 

26.29 

0.95449 

36.80 

29.61 

2S 

0.96119 

30  85 

25.34 

24.35 

0.95792 

33  35 

27.48 

26.33 

0.95441 

35.86 

29.65 

28 

0  96112 

30  90 

25.38 

24.39 

0.95785 

33  40 

27.52 

26.36 

0.95434 

35  90 

29.69 

28 

0.96106 

30  95 

25.42 

24.43 

0.95778 

33.45 

27.56 

26.40 

0.95426 

36.95 

29.73 

28 

0.96100 

31  00 

25.46 

24.47 

0.95771 

33.50 

27.61 

26.44 

0.95419 

36.00 

29.78 

28 

0.96094 

31.05 

25.50 

24.51 

0.95764 

33  55 

27.65 

26.48 

0.95412 

36.05 

29.82 

28 

0.96088 

31  10 

25.55 

24.55 

0.95757 

33.60 

27.70 

26.52 

0.95405 

36  10 

29.87 

28 

0.96082 

31.15 

25.59 

24.59 

0.95751 

33  65 

27.74 

26.56 

0.95397 

36.15 

29.91 

28 

0.96075 

31.20 

25.63 

24.63 

0.95745. 

33.70 

27.78 

26.60 

0.95390 

36.20 

29.95 

28 

0.96069 

31.25 

25.67 

24.67 

0.95738 

33  75 

27.82 

26.64 

0.95382 

36.25 

29.99 

28 

0.96062 

31.30 

25.72 

24.71 

0.95731 

33  80 

27.87 

26.68 

0.95375 

36  30 

30.04 

28 

9.96056 

31.35 

25.76 

24.75 

0.95724 

33.85 

27.91 

26.72 

0.95367 

36.35 

30.09 

28 

0.96049 

31.40 

25.81 

24.79 

0.95717 

33.90 

27.96 

26.76 

0.95360 

36.40 

30.13 

28 

0.96043 

31.46 

25.85 

24.83 

0.95710 

33.96 

28.00 

26.80 

0.95353 

36.46 

30.17 

28. 

0.96036 

31  60 

25.89 

24.86 

0.95703 

34  00 

28.04 

26.84 

0.95346 

36.60 

30.22 

28 

0.96030 

31.65 

25.93 

24.90 

0.95696 

34  05 

28.08 

26.88 

0.95338 

36.66 

30.26 

28. 

0.96024 

31.60 

25.98 

24.94 

0.95689 

34.10 

28.13 

26.92 

0.95331 

36.60 

30.31 

28 

0.96018 

31.66 

26.02 

24.98 

0.95682 

34.15 

28.17 

26.96 

0.95323 

36.66 

30.35 

28 

0.98011 

31.70 

26.06 

25.02 

0.95675 

34.20 

28.22 

26.99 

0.95315 

36.70 

30.39 

28 

XVI] 

WINES 

199 

Table  16.— Alcohol  Table.— Continued. 

ICIFIC 

ALCOHOL 

SPECIFIC 

ALCOHOL 

SPECIFIC 

ALCOHOL 

..VITY 

•c. 

Per  cent 

Per 

Grams 

20°  C. 

Per  cent 

Per 

Grams 

CinAVITY 

20°  C. 

Per  cent 

Per 

Grama 

■o 

by  volume 

cent  by 

per 

4° 

by  volume 

cent  by 

per 

4° 

by  volume 

cent  by 

per 

at  20°  C. 

weight 

100  cc. 

at20°C. 

weight 

100  cc. 

at  20°  C. 

weight 

100  cc. 

0!53OS 

36  75 

SO.  43 

29.01 

0.94926 

39  25 

32.63    30.99 

0.94519 

41.76 

34.86 

32.96 

0  5301 

36  80 

so  48 

29.05 

0.94918 

39  30 

32.68    31.02 

0.94510 

41  80 

34-91 

33.00 

0  5294 

36  85 

SO.  52 

29.09 

0.94910 

39  35 

32.72    31.06 

0.94502 

41.85 

34.95 

33,04 

0i5287 

36  90 

SO.  57 

29.13 

0.94901 

39.40 

32.77    31.10 

0.94494 

41.90 

35.00 

33,07 

015279 

36  95 

SO.  61 

29.17 

0.94893 

39.45 

32.81     31.14 

0.94486 

41.96 

35.04 

33.11 

015272 

37  00 

30.66 

29.21 

0.94885 

39  50 

32.86    31.18 

0.94477 

42.00 

35.09 

33.15 

Di5264 

37  05 

30.70 

29.25 

0.94877 

39.55 

32.90    31.22 

0.94469 

42.05 

35.13 

33,19 

05257 

37  10 

30.74 

29.29 

0.94869 

39  60 

32.95    31.26 

0.94460 

42.10 

35.18 

33,23 

0  5249 

37  15 

30.78 

29.33 

0.94861 

39  65 

32.99    31.30 

0.94452 

42.16 

35.22 

33.27 

0  5242 

37  20 

30.83 

29.36 

0.94853 

39.70 

S3. 04    31.34 

0.94443 

42.20 

35.27 

33.31 

0I5234 

37  25 

30.87 

29.40 

0.94845 

39  75 

S3. 08    31.38 

0.94435 

42  25 

35.31 

33.35 

)l5227 

37  30 

30.92 

29.44 

0.94837 

39  80 

33.13    31.42 

0.94427 

42  30 

35.36 

33.39 

M5219 

37  35 

30.96 

29.48 

0.94829 

39.85 

33.17    31.46 

0.94419 

42  35 

35.40 

33.43 

[^'5211 

37.40 

31.01 

29.52 

0.94821 

39.90 

33.22    31.50 

0.94410 

42.40 

35.45 

33.47 

0C5203 

37  45 

SI. 05 

29.56 

0.94813 

39.95 

33.26    31.54 

0.94402 

42.45 

35.49 

33.51 

45196 

37.50 

31.09 

29.60 

0.94805 

40.00 

33.30    31.57 

0.94393 

42  50 

35.54 

33.55 

W5188 

37  55 

31.13 

29.64 

0.94797 

40.05 

SS.S4    31.61 

0.94385 

42  55 

35.58 

33.59 

tt5181 

37.60 

31.18 

29,68 

0.94789 

40.10 

33.39    31.65 

0.94376 

42  60 

35.63 

33,63 

D5173 

37  65 

31.22 

29.72 

0.94781 

40.15 

3S.4S    31.69 

0.94368 

42  65 

35.67 

33.67 

0|»5166 

37.70 

31.27 

29.76 

0.94773 

40.20 

3S.48    31.73 

0.94359 

42.70 

35.72 

33.71 

0  to  158 

37  75 

SI. 31 

29.80 

0.94765 

40  25 

33.52    31.77 

0.94351 

42.75 

35.76 

33.75 

05151 

37.80 

31.36 

29.84 

0.94757 

40.30 

33.57    31.81 

0.94342 

42.80 

35.81 

33.78 

(!t51  13 

37  85 

31. 40 

29.88 

0.94749 

40  35 

33.61     31.85 

0.94334 

42.85 

35.85 

33,82 

rt.")!:;.') 

37  90 

31.45 

29.92 

0.94741 

40  40 

33.66    31.89 

0.94325 

42  90 

35.90 

33,86 

(t:.iJ7 

37  95 

31.49 

29.96 

0.94733 

40.45 

33.70    31.93 

0.94317 

42.95 

35.94 

33.90 

rt.ii'-'o 

38  00 

31.53 

29.99 

0.94725 

40  60 

SS.75    31.97 

0.94308 

43.00 

35.99 

33.94 

Of)  11 2 

38  05 

SI.  57 

30.03 

0.94717 

40  55 

33.79    32.01 

0.94300 

43  05 

36.03 

33.98 

05104 

38  10 

31.62 

30.07 

0.94708 

40  60 

33.84    32.05 

0.94291 

42.10 

36.08 

34.02 

05090 

38  15 

31.66 

30.11 

0.94700 

40  65 

33.88    32.09 

0.94283 

43.15 

36.12 

34.06 

C)50S9 

38  20 

31.71 

30.15 

0.94692 

40.70 

33.93    32.13 

0.94274 

43  20 

36.17 

34.10 

(t50si 

38  25 

31.75 

30.19 

0.94684 

40  75 

SS.97    32.17 

0.94265 

43.26 

36.21 

34.14 

( t.ior  4 

38  30 

31.80 

30.23 

0.94676 

40.80 

34.02    32.20 

0.94256 

43  30 

36.26 

34.18 

(»50C.() 

38  35 

31.84 

30.27 

0.94668 

40.85 

34.06    32.24 

0.94248 

43  36 

36  SO 

34,22 

( )5o:)X 

38  40 

SI.  89 

30.31 

0.94659 

40  90 

34-11     32.28 

0.94239 

43  40 

36  35 

34,26 

()50.')0 

38  45 

31.93 

30.35 

0.94651 

40.95 

34.15    32.32 

0.94231 

43.45 

36.39 

34.30 

( t.')!)):; 

38  50 

31.97 

30.39 

0.94643 

41  00 

34.19    32.36 

0.94222 

43  60 

36.44 

34.34 

( >.■)():',.") 

38  55 

32.01 

30.43 

0.94635 

41  05 

34.23    32.40 

0.94214 

43  55 

36.48 

34.38 

O5027 

38  60 

32.06 

30.47 

0.94627 

41  10 

34.28    32.44 

0,04205 

43  60 

S>:.53 

34.42 

05019 

38  65 

32.10 

30.51 

0.94619 

41  15 

34-32    32.48 

0.94197 

43  65 

36.57 

34.46 

n:,n  11 

38  70 

32.15 

30.55 

0.94610 

41  20 

34-37    32.52 

0.94188 

43  70 

36.62 

34.49 

1  iriOi  )■; 

38  75 

32.19 

30.59 

0.94602 

41  25 

34.41     32.56 

0.94179 

43  75 

36.66 

34.53 

(  Mit'.tO 

38.80 

32.24 

30.63 

0.94594 

41  30 

S4-46    32.60 

0,94170 

43  80 

36.71 

34.57 

( )49SS 

38  85 

32.28 

30.67 

0.94586 

41  35 

34-50    32.64 

0,94161 

43  85 

S6 .  75 

34.61 

CM!tS() 

38  90 

32.33 

30.71 

0.94577 

41  40 

34-55    32.68 

0.94152 

43  90 

36.80 

34.65 

C|)4972 

38  95 

32. S7 

30.75 

0.94569 

41.46 

34.59    32.72 

0,94144 

43  95 

36.84 

34  69 

04904 

39  00 

32.42 

30.79 

0.94560 

41  60 

34-64    32.76 

0,94135 

44  00 

36.89 

34.73 

049:,(; 

39  05 

32.46 

30.83 

0.94552 

41  56 

S4-68    32.80 

0,94126 

44  05 

36.94 

34.77 

ft494() 

39  10 

32.51 

30.87 

0.94544 

41.60 

34-73    32.84 

0.94117 

44  10 

36.99 

34.81 

U4941 
Cj)4934 

39.15 

32.55 

30.91 

0.94536 

41  65 

34.77    32.88 

0.9410S 

44.15 

37.03 

34.85 

39  20 

32.59 

30.95 

0.94527 

41.70 

S4.82    32.92 

0.94099 

44  20 

37.08 

34.89 

200 


METHODS    OF   ANALYSIS 


[Chap. 


5 

Table  16.— Alcohol  Table.- 

—Continued. 

SPECIFIC 

ALCOHOL 

SPECIFIC 

ALCOHOL 

SPECIFIC 

ALCOHOL 

°20°''c.'' 

Per  cent 

Per 

Grams 

*'20°''c.^ 

Per  cent 

Per 

Grams 

''w^c^ 

Per  cent 

Per 

Gra 

4° 

by  volume 

cent  by 

per 

4° 

by  volume 

cent  by 

per 

4° 

by  volume 

cent  by 

pe 

at  20°  C. 

weight 

100  cc. 

at  20°  C. 

weight 

100  cc. 

at  20°  C. 

weight 

100 

0.94091 

44.25 

37.12 

34.93 

0.93638 

46  75 

39.41 

36.90 

0.93164 

49.26 

41.72 

38. 

0.94082 

44  30 

37.17 

34.97 

0.93629 

46  80 

39.46 

36.94 

0.93155 

49  30 

41.77 

38. 

0.94073 

44.35 

37.21 

35.01 

0.93619 

46  85 

39.50 

36.98 

0.93145 

49  35 

41.82 

38. 

0.94064 

44.40 

37.26 

35.05 

0.93610 

46  90 

39.55 

37.02 

0.93136 

49.40 

41.87 

38. 

0.94055 

44.45 

37.30 

35.09 

0.93600 

46  95 

39.59 

37.06 

0.93126 

49.45 

41.91 

39. 

0.94046 

44  50 

37.35 

35.13 

0.93591 

47.00 

39.64 

37.10 

0.93116 

49  50 

41.96 

39. 

0.94037 

44.55 

37.39 

35.17 

0.93582 

47.05 

39.68 

37.14 

0.93106 

49.55 

42.01 

39. 

0.94028 

44.60 

37.  U 

35.20 

0.93573 

47.10 

39.73 

37.18 

0.93096 

49.60 

42.06 

39. 

0.94020 

44.65 

37.48 

35.24 

0.93563 

47.15 

39.77 

37.22 

0.93086 

49.65 

42.10 

39. 

0.94011 

44.70 

37.53 

35.28 

0.93554 

47.20 

39.82 

37.26 

0.93076 

49.70 

42.15 

39. 

0.94002 

44.75 

37.57 

35.32 

0.93545 

47.25 

39.87 

37.30 

0.93066 

49  75 

42.19 

39. 

0.93993 

44  80 

37.62 

35.36 

0.93536 

47  30 

39.92 

37.34 

0.93056 

49  80 

42.24 

39. 

0.93984 

44.85 

37.66 

35.40 

0.93526 

47  35 

39.96 

37.38 

0.93046 

49  85 

42.29 

39. 

0.93975 

44  90 

37.71 

35.44 

0.93517 

47.40 

40.01 

37.42 

0.93036 

49  90 

42.34 

39. 

0.93966 

44.95 

37.75 

35.48 

0.93507 

47.45 

40.05 

37.46 

0.93026 

49  95 

42.38 

39. 

0.93957 

45  00 

37.80 

35.52 

0.93498 

47  50 

40.10 

37.49 

0.93017 

50  00 

42.43 

39. 

0.93948 

45.05 

37.85 

35.56 

0.93488 

47  55 

40.14 

37.53 

0.93007 

50  05 

42.47 

39. 

0.93939 

45.10 

37.90 

35.60 

0.93479 

47.60 

40.19 

37.57 

0.92997 

50.10 

42.52 

39. 

0.93931 

45.15 

37.94 

35.64 

0.93470 

47.65 

40.24 

37.61 

0.92987 

50  15 

42.57 

39. 

0.93922 

45.20 

37.99 

35.68 

0.93461 

47.70 

40.29 

37.65 

0.92977 

50.20 

42.62 

39. 

0.93912 

45  25 

38.03 

35.72 

0.93451 

47.75 

40.33 

37.69 

0.92967 

60  25 

42.66 

39. 

0.93903 

45  30 

38.08 

35.76 

0.93442 

47.80 

40.38 

37.73 

0.92957 

50  30 

42.71 

39. 

0.93894 

45.35 

38.12 

35.80 

0.93432 

47.85 

40.42 

37.77 

0.92947 

50  35 

42.76 

39. 

0.93885 

45.40 

38.17 

35.84 

0.93423 

47.90 

40.47 

37.81 

0.92938 

50  40 

42.81 

39. 

0.93876 

45.45 

38.21 

35.88 

0.93413 

47.95 

40.51 

37.85 

0.92928 

60.46 

42.85 

39. 

0.93867 

45  50 

38.26 

35.92 

0.93404 

48  00 

40.56 

37.89 

0.92918 

50  60 

42.90 

39. 

0.93858 

45  55 

38.30 

35.86 

0.93394 

48  05 

40.61 

37.93 

0.92908 

60.56 

42.94 

39. 

0.93849 

45  60 

38.35 

35.99 

0.93385 

48  10 

40.66 

37.97 

0.92898 

60  60 

42.99 

39. 

0.93840 

45  65 

38.39 

36.03 

0.93375 

48.15 

40.70 

38.01 

0.92888 

50  65 

43.04 

39. 

0.93831 

45.70 

38.44 

36.07 

0.93366 

48.20 

40.75 

38.05 

0.92879 

50.70 

43.09 

40. 

0.93822 

45.76 

38.49 

36.11 

0.93356 

48.25 

40.79 

38.09 

0.92869 

50  76 

43.13 

40. 

0.93813 

45.80 

38.54 

36.15 

0.93347 

48  30 

40.84 

38.13 

0.92859 

60  80 

43.18 

40. 

0.93803 

45.85 

38.58 

36.19 

0.93337 

48  35 

40.89 

38.17 

0.92849 

50  85 

43.23 

40. 

0.93794 

45.90 

38.63 

36.23 

0.93328 

48  40 

40.94 

38.21 

0.92839 

50  90 

43.28 

40. 

0.93785 

45.95 

38.67 

36.27 

0.93318 

48.45 

40.98 

38.25 

0.92829 

50  96 

43.32 

40. 

0.93776 

46  00 

38.72 

36.31 

0.93308 

48.50 

41.03 

38.29 

0.92818 

61  00 

43.37 

40. 

0.93767 

46  05 

38.76 

36.35 

0.93298 

48  65 

41.07 

38.33 

0.92808 

51  06 

43.42 

40. 

0.93758 

46.10 

38.81 

36.39 

0.93289 

48  60 

41.12 

38.36 

0.92798 

51.10 

43.47 

40. 

0.93749 

46.15 

38.85 

36.43 

0.93279 

48  65 

41.16 

38.40 

0.92788 

51.15 

43.51 

40. 

0.93740 

46.20 

38.90 

36.47 

0.93270. 

48.70 

41.21 

38.44 

0.92778 

51  20 

43.56 

40. 

0.93730 

46  25 

38.95 

36.51 

0.93260 

48.75 

41.26 

38.48 

0.92768 

51  25 

43.60 

40. 

0.93721 

46  30 

39.00 

36.55 

0.93251 

48  80 

41.31 

38.52 

0.92759 

51  30 

43.65 

40. 

0.93712 

46  35 

39.04 

36.59 

0.93241 

48.85 

41.35 

38.56 

0.92749 

51  35 

43.70 

40. 

0.93703 

46  40 

39.09 

36.63 

0.93232 

48.90 

41.40 

38.60 

0.92739 

61  40 

43.75 

40. 

0.93693 

46.45 

39.13 

36.67 

0.93222 

48.95 

41.44 

38.64 

0.92729 

51.46 

43.79 

40. 

0.93684 

46  50 

39.18 

36.70 

0.93213 

49  00 

41.49 

38.68 

0.92719 

51  60 

43.84 

40. 

0.93675 

46.55 

39.22 

36.74 

0.93203 

49.05 

41.54 

38.72 

0.92709 

61.56 

43.89 

40. 

0.93666 

46.60 

39.27 

36.78 

0.93194 

49  10 

41.59 

38.76 

0.92699 

51.60 

43.94 

40. 

0.93656 

46.65 

39.31 

36.82 

0.93184 

49.15 

41.63 

38.80 

0.92689 

51  66 

43.98 

40. 

0.93647 

46.70 

39.36 

36.86 

0.93174 

49  20 

41.68 

38.83 

0.92678 

51.70 

44.03 

40. 

XVI] 

WINES 

201 

Table  16.— Alcohol  Table.— Continued. 

ALCOHOL 

ALCOHOL 

lLCOHOL 

■%C1FIC 

SPECIFIC 

SPECIFIC 

6.VITY 

}°  c. 

Per  cent 

Per 

Grams 

GRAVITY 
20°  C. 

Per  cent 

Per 

Grama 

20°  C. 

Per  cent 

Per 

Grama 

by  volume 

cent  by 

per 

4° 

by  volume 

cent  by 

per 

4° 

by  volume 

cent  by 

per 

r 

at  20°  C. 

weight 

100  cc. 

at20°C. 

weight 

100  cc. 

at  20°  C. 

weight 

100  cc. 

0^2668 

61.75 

U08 

40.85 

0.92157 

64  26 

46.46 

42.82 

0.91629 

56  75 

48.89 

44,80 

02658 

51  80 

U.15 

40.89 

0.92147 

54  30 

46.51 

42.86 

0.91618 

56  80 

48.94 

44,83 

0  2648 

51  85 

U.17 

40.93 

0.92137 

54  36 

46.56 

42.90 

0.91608 

56  85 

48.98 

44,87 

02637 

51  90 

U.22 

40.97 

0.92126 

64  40 

46.61 

42.94 

0.91597 

56  90 

49.03 

44.91 

0!2627 

51  95 

U.26 

41.01 

0.92116 

64.45 

46.66 

42.98 

0.91586 

66.96 

49.08 

44.95 

02617 

52  00 

U.Sl 

41.05 

0.92105 

54.60 

46.71 

43.02 

0.91575 

57  00 

49.13 

44.99 

i  _'('i07 

62  05 

U.S6 

41.09 

0.92095 

64  65 

46.75 

43.06 

0.91565 

57  06 

49.18 

45.03 

)  -'.V.i7 

52  10 

U41 

41.13 

0.92084 

64  60 

46.80 

43.10 

0.91554 

57  10 

49.23 

45.07 

012587 

52  15 

U46 

41.17 

0.92074 

64.65 

46.85 

43.14 

0.91543 

57.15 

49.28 

45.11 

0|2577 

62  20 

U.51 

41.20 

0.92063 

64  70 

46.90 

43.18 

0.91532 

67.20 

49.33 

45.15 

1  2507 

52  26 

U.55 

41.24 

0.92053 

54.76 

46.94 

43.22 

0.91521 

67  26 

49.38 

45.19 

52  30 

U.60 

41.28 

0.92042 

54  80 

46.99 

43.26 

0.91510 

67  30 

49.43 

45.23 

1  ir,\7 

62  36 

U.65 

41.32 

0.92032 

64  85 

47.04 

43.30 

0.91500 

57  35 

49.47 

45.27 

52  40 

U.70 

41.36 

0.92021 

64  90 

47.09 

43.34 

0.91489 

67  40 

49.52 

45.31 

1  .':.L'7 

62  46 

U.7i 

41.40 

0.92011 

54  95 

47.14 

43.38 

0.91478 

57.46 

49.57 

45.35 

0  2516 

62  50 

U-79 

41,44 

0.92000 

65  00 

47.19 

43.42 

0.91467 

67  50 

49.62 

45.39 

0  2506 

52  55 

UM 

41.48 

0.91990 

56  06 

47.24 

43.46 

0.91457 

67  55 

49.67 

45.43 

0  2406 

52  60 

U.89 

41.52 

0.91979 

65  10 

47.29 

43.49 

0.91446 

57.60 

49.72 

45.47 

)  :IS(i 

52  65 

U.93 

41.56 

0.91969 

55.16 

47.33 

43.53 

0.91435 

67  66 

49.77 

45.51 

i  .'  176 

52  70 

U.98 

41.60 

0.91958 

65.20 

47.38 

43.57 

0.91424 

57.70 

49.82 

45.55 

0.2466 

52  75 

45.03 

41.64 

0.91948 

56  26 

47.43 

43.61 

0.91414 

57.76 

49.87 

45.59 

0.2455 

52  80 

45.08 

41.68 

0.91937 

55  30 

47.48 

43.65 

0.91403 

67.80 

49.92 

45.63 

0.2445 

52  86 

45.12 

41.72 

0.91927 

65  36 

47.53 

43.69 

0.91392 

57.86 

49.96 

45.67 

0  2434 

52  90 

45.17 

41.76 

0.91916 

56  40 

47.58 

43.73 

0.91381 

57  90 

50.01 

45.70 

0  2424 

52  96 

45.22 

41.80 

0.91906 

65  46 

47.62 

43.77 

0.91370 

57.95 

50.06 

45.74 

_M!  I 

53  00 

45.27 

41.83 

0.91895 

65  60 

47.67 

43.81 

0.91359 

58.00 

50.11 

45.78 

.'inl 

63  05 

45.31 

41.87 

0.91885 

56  55 

47.72 

43.85 

0.91348 

58  05 

50.16 

45.82 

'  1 

53  10 

45.36 

41.91 

0.91874 

55  60 

47.77 

43.89 

0.91337 

58  10 

50.21 

45.86 

1 

53  16 

45.41 

41.95 

0.91864 

56  66 

47.82 

43.93 

0.91326 

58  15 

50.26 

45.90 

63  20 

45.46 

41.99 

0.91853 

56.70 

47.87 

43.97 

0.91315 

68  20 

50.31 

45.94 

53  26 

45.51 

42.03 

0.91842 

55  75 

47.91 

44.01 

0.91304 

68.26 

50.36 

45.98 

53  30 

45.56 

42.07 

0.91831 

66.80 

47.96 

44.04 

0.91293 

68  30 

50.41 

46.02 

53  35 

45.60 

42.11 

0.91821 

65  85 

48.01 

44.08 

0.91282 

58  36 

50.46 

46,06 

53  40 

45.65 

42.15 

0.91810 

66  90 

48.06 

44.12 

0.91271 

58  40 

50.51 

46.10 

53  46 

45.70 

42.19 

0.91800 

55  95 

48.11 

44.16 

0.91261 

58.45 

50.55 

46.14 

53  50 

45.75 

42.23 

0.91789 

56  00 

48.16 

44.20 

0.91250 

68  60 

50.60 

46.17 

53  55 

45.79 

42.27 

0.91779 

56.06 

48.20 

44.24 

0.91239 

68  55 

50.65 

46.21 

53  60 

45.84 

42.31 

0.91768 

56  10 

48.25 

44.28 

0.91228 

58.60 

50.70 

46.25 

! 

53  65 

45.89 

42.35 

0.91758 

56  15 

48.30 

44.32 

0.91217 

58  65 

50.75 

46.29 

^■71 

53  70 

45.94 

42.39 

0.91747 

56  20 

48.35 

44.36 

0.91206 

58.70 

50.80 

46.33 

'■-.] 

53  76 

45.98 

42.43 

0.91736 

56  25 

48.40 

44.40 

0.91194 

58.75 

50.85 

46.37 

', 

63  80 

46.03 

42.47 

0.91725 

56  30 

48.45 

44.44 

0.91183 

58  80 

50.90 

46.41 

1 

53  85 

46.08 

42.51 

0.91715 

56  35 

48.50 

44.48 

0.91171 

58  85 

50.95 

46.45 

'  ::) 

53.90 

46.13 

42.55 

0.91704 

56  40 

48.55 

44.52 

0.91160 

58  90 

51.00 

46.49 

O.|;220 

63  96 

46.18 

42.59 

0.91694 

56  45 

48.59 

44.56 

0.91149 

58  95 

51.05 

46.53 

11  >ona 

54  00 

46.23 

42.62 

0.91683 

66  50 

48.64 

44.60 

0.91138 

59  00 

51.10 

46.57 

,..,, 

54  06 

46.27 

42.66 

0.91672 

56  55 

48.69 

44.64 

0,91127 

59  05 

51.15 

46.61 

64  10 

46.32 

42.70 

0.91661 

56.60 

48.74 

44.68 

0.91116 

59.10 

51.20 

46.65 

u    A  is 

64.15 

46.36 

42.74 

0.91650 

56  65 

48.79 

44.72 

0.91104 

59.15 

51.25 

46.69 

0.|J167 

64.20 

46.41 

42.78 

0.91639 

56.70 

48.84 

44.76 

0.91093 

59  20 

51.30 

46.73 

202 


METHODS    OF   ANALYSIS 


[Chap. 


5 

Table  16.— Alcohol  Table.- 

—Continued. 

SPECIFIC 

ALCOHOL 

SPECIFIC 

ALCOHOL 

SPECIFIC 

ALCOHOL 

20°  C. 

Per  cent 

Per     1 

Grams 

20°  C. 

Per  cent 

Per 

Grams 

20°  C. 

Per  cent 

Per 

Gn 

4° 

by  volume 

cent  by 

per 

4° 

by  volume 

cent  by 

per 

4° 

by  volume 

cent  by 

P< 

at  20°  C. 

weight 

100  cc. 

at  20°  C. 

weight 

100  CO. 

at  20°  C. 

weight 

100 

0.91082 

59  26 

51.  S5 

46.77 

0.90520 

61.75 

53.85 

48.74 

0.89942 

64.25 

56.39 

50 

0.91071 

59  30 

5140 

46.81 

0.90509 

61.80 

53.90 

48.78 

0.89930 

64  30 

56.44 

50 

0.91060 

59  36 

5145 

46.85 

0.90497 

61.85 

53.95 

48.82 

0.89918 

64.35 

56.49 

50 

0.91049 

59  40 

51.50 

46.89 

0.90486 

61.90 

54.00 

48.86 

0.89907 

64.40 

56.54 

50 

0.91038 

69  46 

51.55 

46.93 

0.90474 

61.96 

54.05 

48.90 

0.89895 

64.45 

56.59 

50 

0.91027 

59  60 

51.60 

46.97 

0.90463 

62  00 

54.10 

48.94 

0.89884 

64.50 

56.64 

50 

0.91016 

59  56 

51.65 

47.01 

0.90451 

62  05 

54.15 

48.98 

0.89872 

64  66 

56.70 

50 

0.91005 

69  60 

51.70 

47.05 

0.90440 

62.10 

54.20 

49.02 

0.89861 

64.60 

56.75 

50 

0.90993 

59  66 

51.7J^ 

47.09 

0.90428 

62.15 

54.25 

49.06 

0.89849 

64.66 

56.80 

51 

0.90982 

69  70 

51.79 

47.12 

0.90417 

62.20 

54.30 

49.10 

0.89837 

64.70 

56.85 

51 

0.90971 

59.75 

51.84 

47.16 

0.90406 

62  26 

54.35 

49.14 

0.89825 

64.75 

56.90 

51 

0.90960 

59  80 

51.89 

47.20 

0.90395 

62  30 

54.40 

49.18 

0.89814 

64.80 

66.95 

51 

0.90949 

59  85 

51.94 

47.24 

0.90383 

62  36 

54.45 

49.22 

0.89802 

64.85 

57.00 

51 

0.90938 

69  90 

51.99 

47.28 

0.90372 

62.40 

54.50 

49.25 

0.89791 

64.90 

57.05 

51 

0.90926 

59  95 

52.04 

47.32 

0.90360 

62.46 

54.55 

49.29 

0.89779 

64.95 

57.11 

51 

0.90915 

60  00 

52.09 

47.36 

0.90349 

62  50 

5  4. 60 

49.33 

0.89767 

65  00 

57.16 

51 

0.90904 

60  05 

52.14 

47.40 

0.90337 

62  55 

54.66 

49.37 

0.89755 

65  06 

57.21 

51 

0.90893 

60  10 

52.19 

47.44 

0.90326 

62  60 

54.71 

49.41 

0.89744 

65.10 

57.26 

51 

0.90882 

60  15 

52.24 

47.48 

0.90314 

62.65 

54.76 

49.45 

0.89732 

65.15 

57.31 

51 

0.90871 

60  20 

52.29 

47.52 

0.90302 

62  70 

54. 81 

49.49 

0.89720 

65.20 

57.38 

51 

0.90859 

60.25 

52. S4 

47.56 

0.90290 

62.76 

54.86 

49.53 

0.89708 

66  25 

57.41 

51 

0.90848 

60  30 

52.39 

47.60 

0.90279 

62  80 

54.91 

49.57 

0.89696 

65  30 

57.46 

51 

0.90837 

60  36 

52.44 

47.64 

0.90267 

62.85 

54.96 

49.61 

0.89684 

65  35 

57.52 

51 

0.90826 

60  40 

52.49 

47.68 

0.90256 

62.90 

55.01 

49.65 

0.89672 

65.40 

57.57 

51 

0.90814 

60  46 

52.54 

47.72 

0.90244 

62.95 

55.06 

49.69 

0.89660 

65  46 

57.62 

51 

0.90803 

60  50 

52.59 

47.76 

0.90233 

63  00 

55.11 

49.73 

0.89649 

65  50 

57.67 

51 

0.90792 

60  66 

52.64 

47.80 

0.90221 

63  05 

55.16 

49.77 

0.89637 

66  65 

57.72 

51 

0.90781 

60  60 

52.69 

47.84 

0.90210 

63  10 

55.21 

49.81 

0.89626 

65.60 

57.77 

51 

0.90769 

60  65 

52.74 

47.88 

0.90198 

63  15 

55.26 

49.85 

0.89614 

65.66 

57.83 

51 

0.90758 

60  70 

52.79 

47.91 

0.90187 

63.20 

55.31 

49.89 

0.89602 

66.70 

57.88 

51 

0.90747 

60  75 

52.84 

47.95 

0.90175 

63  26 

55.37 

49.93 

0.89590 

66  75 

57.93 

51 

0.90736 

60  80 

52.89 

47.99 

0.90163 

63  30 

55.42 

49.97 

0.89578 

65  80 

57.98 

51 

0.90724 

60  86 

52.94 

48.03 

0.90151 

63  35 

55.47 

50.01 

0.89566 

65.86 

58.04 

51 

0.90713 

60.90 

52.99 

48.07 

0.90140 

63  40 

55.52 

50.04 

0.89554 

65  90 

58.09 

52 

0.90701 

60  96 

53.04 

48.11 

0.90128 

63  45 

55.57 

50.08 

0.89542 

65  95 

58.14 

52 

0.90690 

61  00 

53.09 

48.15 

0.90117 

63  60 

55.62 

50.12 

0.89531 

66.00 

58.19 

52 

0.90678 

61  05 

53.14 

48.19 

0.90105 

63.55 

55.67 

50.16 

0.89519 

66.06 

58.24 

52 

0.90667 

61  10 

53.19 

48.23 

0.90094 

63  60 

55.72 

50.20 

0.89507 

66.10 

58.29 

52 

0.90656 

61  16 

53.24 

48.27 

0.90082 

63  65 

55.77 

50.24 

0.89495 

66  15 

58.35 

52 

0.90645 

61  20 

53.29 

48.31 

0.90070 

63  70 

55.82 

50.28 

0.89483 

66.20 

58.40 

52 

0.90633 

61  26 

53.34 

48.35 

0.90059 

63.75 

55.88 

50.32 

0.89471 

66.25 

58.45 

52 

0.90622 

61.30 

53.39 

48.39 

0.90048 

63  80 

55.93 

50.36 

0.89459 

66.30 

58.50 

52 

0.90610 

61  35 

53.44 

48.43 

0.90036 

63.85 

55.98 

50.40 

0.89447 

66  35 

58.55 

52 

0.90599 

61.40 

53.49 

48.47 

0.90025 

63.90 

56.03 

50.44 

0.89435 

66.40 

58.60 

52 

0.90588 

61  45 

53.55 

48.51 

0.90013 

63.96 

56.08 

50.48 

0.89423 

66.46 

68.66 

52 

0.90577 

61  50 

53.60 

48.55 

0.90001 

64.00 

56.13 

50.52 

0.89411 

66  50 

58.71 

52 

0.90565 

61.55 

53.65 

48.59 

0.89989 

64  05 

56.18 

50.56 

0.89399 

66  55 

58.76 

52 

0.90554 

61.60 

53.70 

48.62 

0.89978 

64.10 

56.23 

50.60 

0.89387 

66.60 

68.81 

52 

0.90543 

61.66 

53.75 

48.66 

0.89966 

64.15 

56.29 

50.64 

0.89375 

66.66 

58.87 

52 

0.90532 

61  70 

53.80 

48.70 

0.89954 

64.20 

56.34 

50.68 

0.89363 

66  70 

68.92 

52 

XVI] 

WINES 

203 

Table  16.— Alcohol  Table.— Continued. 

1  5CIFIC 

ALCOHOL 

SPECIFIC 

ALCOHOL 

SPECIFIC 

ALCOHOL 

CAVITY 

!)°c. 

Per  cent 

1     Per 

Grams 

GRAVITY 

20°  C. 

Per  cent 

Per 

Grams 

GRAVITY 

20°  C. 

Per  cent 

Per 

Grams 

1° 

by  volume  cent  by 

per 

4° 

by  volume  cent  by 

per 

4° 

by  velum 

e  cent  by 

per 

at20°C. 

1  weight 

100  cc. 

at  20°  C. 

weight 

100  cc. 

at  20°  C. 

weight 

100  cc. 

p|{9351 

66  75 

58.97 

52.69 

0.88744 

69  26 

61.60 

54.66 

0.88120 

71.75 

64-27 

56.64 

19339 

66  80 

59.02 

52.73 

0.88732 

69  30 

61.65 

54.70 

0.88107 

71  80 

64.32 

56.68 

Ht9327 

66  85 

59.07 

52.77 

0.88720 

69  35 

61.70 

54.74 

0.88094 

71  85 

64.38 

56.72 

K9315 

66  90 

59.12 

52.81 

0.88707 

69  40 

61.75 

54.78 

0.88081 

71  90 

64-43 

56.75 

0^9303 

66  95 

59.18 

52.85 

0.88695 

69  45 

61.81 

54.82 

0.88069 

71  95 

64-49 

56.79 

0  9291 

67  00 

59.23 

52.89 

0.&S682 

69  50 

61.86 

54.86 

0.88056 

72  00 

64-54 

56.83 

0^9279 

67  05 

59.28 

52.93 

0.88670 

69  55 

61.92 

54.90 

0.88044 

72  05 

64-60 

56.87 

019267 

67  10 

59.33 

52.97 

0.88658 

69  60 

61.97 

54.94 

0.88031 

72  10 

64-65 

56.91 

019255 

67  15 

59.39 

53.01 

0.88646 

69  65 

62.02 

54.98 

0.88018 

72  16 

64-71 

56.95 

019243 

67  20 

59.  A^ 

53.04 

0.88633 

69.70 

62.07 

55.02 

0.88005 

72  20 

64-76 

56.99 

[)i9231 

67  25 

59.49 

53.08 

0.88621 

69  75 

62.13 

55.06 

0.87993 

72  25 

64-82 

57.03 

09219 

67  30 

59.54 

53.12 

0.88608 

69.80 

62.18 

55.10 

0.87980 

72  30 

64-87 

57.07 

O!9207 

67  35 

59.60 

53.16 

0.88596 

69  85 

62.24 

55.14 

0.87967 

72  36 

64-93 

57.11 

D0195 
B 19183 

67  40 

59.65 

53.20 

0.88583 

69  90 

62.29 

55.18 

0.87954 

72  40 

64.98 

57.15 

67  45 

59.70 

53.24 

0.88571 

69  95 

62.34 

55.22 

0.87942 

72  46 

65.03 

57.19 

09171 

67  60 

59.75 

53.28 

0.88558 

70.00 

62.39 

55.25 

0.87929 

72  60 

65.08 

57.23 

09159 

67  55 

59.81 

53.32 

0.88546 

70  06 

62.45 

55.29 

0.87916 

72  55 

65.14 

57.27 

019147 

67  60 

59.86 

53.36 

0.88533 

70  10 

62.50 

55.33 

0.87903 

72.60 

65.19 

57.31 

019135 

67  65 

59.91 

53.40 

0.88521 

70.15 

62.56 

55.37 

0.87891 

72  65 

65.25 

57.35 

09122 

67  70 

59.96 

53.44 

0.88508 

70  20 

62.61 

55.41 

0.87878 

72  70 

65.30 

57.38 

O^llO 

67  75 

60.02 

53.48 

0.88496 

70  26 

62.66 

55.45 

0.87865 

72  75 

65.36 

57.42 

019098 

67  80 

60.07 

53.52 

0.88484 

70  30 

62.71 

55.49 

0.87852 

72  80 

65.41 

57.46 

0  9osr, 

67  85 

60.12 

53.56 

0.88472 

70  36 

62.77 

55.53 

0.87839 

72  85 

65.47 

57.50 

0  9074 

67  90 

60.17 

53.60 

0.88459 

70  40 

62.82 

55.57 

0.87826 

72  90 

65.52 

57.54 

09002 

67  95 

60.23 

53.64 

0.88447 

70  46 

62.87 

55.61 

0.87813 

72  95 

65.58 

57.58 

obooo 

68  00 

60.28 

53.68 

0.88434 

70  60 

62.92 

55.65 

0.87800 

73  00 

65.63 

57.62 

019038 

68  05 

60.33 

53.72 

0.88422 

70  65 

62.98 

55.69 

0.8VV88 

73  05 

65.69 

57.66 

0  9020 

68  10 

60.38 

53.75 

0.88409 

70  60 

63.03 

55.73 

0.87775 

73  10 

65.74 

57.70 

0  9O14 

68  15 

60.  U 

53.79 

0.88397 

70  65 

63.09 

55.77 

0.87762 

73  15 

65.80 

57.74 

0  9OO1 

68  20 

60.49 

53.83 

0.88384 

70.70 

63.14 

55.81 

0.87749 

73  20 

65.85 

57.78 

0  B989 

68  26 

60.54 

53.87 

0.88372 

70.76 

63.20 

55.85 

0.87737 

73  26 

65.91 

57.82 

0  5977 

68  30 

60.59 

53.91 

0.88359 

70  80 

63.25 

55.89 

0.87724 

73  30 

65.96 

57.86 

)?965 

68  35 

60.65 

53.95 

0.88347 

70  85 

63.31 

55.93 

0.87711 

73  35 

66.02 

57.90 

)§952 

68  40 

60.70 

53.99 

0.88334 

70  90 

63.36 

55.97 

0.87698 

73  40 

66.07 

57.94 

0^940 

68  45 

60.75 

54.03 

0.88322 

70  95 

63.41 

56.01 

0.87685 

73  45 

66.13 

57.98 

OS028 

68  50 

60.80 

54.07 

0.88309 

71  00 

63.46 

56.04 

0.87672 

73  50 

66.18 

58.02 

^M',i 

68  55 

60.86 

54.11 

0.&S297 

71  05 

63.52 

56.08 

0.87659 

73  55 

66.23 

58.06 

68  60 

60.91 

54.15 

0.88284 

71  10 

63.57 

56.12 

0.87646 

73  60 

66. 2S 

58.10 

68  65 

60.96 

54.19 

0.88272 

71  16 

63.63 

56.16 

0.87C)33 

73  66 

66.34 

58.14 

^^i"'' 

68  70 

61.01 

54.23 

0.88259 

71  20 

63.68 

56.20 

0.87620 

73  70 

66.39 

58.17 

^^'-7 

68  75 

61.07 

54.27 

0.88246 

71  26 

63.74 

56.24 

0.87607 

73  75 

66.45 

58.21 

68  80 

61.12 

54.31 

0.88233 

71  30 

63.79 

56.28 

0.87594 

73  80 

66.50 

58.25 

68  85 

61.17 

54.35 

0.88221 

71  36 

63.84 

56.32 

0.87581 

73  85 

66.56 

58.29 

68  90 

61.22 

54.39 

0.88208 

71  40 

63.89 

56.36 

0.87568 

73  90 

66.61 

58.33 

68  95 

61.28 

54.43 

0.88196 

7145 

63.95 

56.40 

0.87555 

73.95 

66.67 

58.37 

69  00 

61.33 

54.47 

0.88183 

71  60 

64.00 

56.44 

0.87542 

74  00 

66.72 

58.41 

69  05 

61.39 

54.51 

0.88171 

71  66 

64.06 

56.48 

0.87529 

74.05 

6'i  rs 

58.45 

69  10 

61.44 

54.54 

0.88158 

71  60 

64.11 

56.52 

0.87516 

74  10 

66.83 

58.49 

»'  >7ni» 

69  15 

61.49 

54.58 

0.88145 

71  65 

64. 17 

56.56 

0.87504 

74.15 

66.89 

58.53 

018756 

69  20 

61.54 

54.62 

0.88132 

71.70 

64.22 

56.60 

0.87491 

74  20 

66.94 

58.57 

204 


METHODS   OF   ANALYSIS 


[Chap. 


Table  16.— Alcohol  Table.— Continued. 


SPECIFIC 

ALCOHOL 

SPECIFIC 

ALCOHOL 

SPECIFIC 

ALCOHOL 

GRAVITY 

20°  C. 

Per  cent 

Per 

Grams 

20°  C. 

Per  cent 

Per 

Grams 

20°  C^ 

Per  cent 

Per 

C 

4° 

by  volume 

cent  by 

per 

4° 

by  volume 

cent  by 

per 

4° 

by  volume 

cent  by 

at  20°  C. 

weight 

100  cc. 

at20°C. 

weight 

100  cc. 

at  20°  C. 

weight 

I 

0.87478 

74,25 

67.00 

58.61 

0.86818 

76.75 

69.78 

60.58 

0.86137 

79.25 

72.63     6 

0.87465 

74  30 

67.05 

58.65 

0,86805 

76  80 

69.84 

60,62 

0.86124 

79  30 

72.68    6 

0.87452 

74  35 

67.11 

58.69 

0.86791 

76  85 

69.90 

60,66 

0,86110 

79  35 

72.74    6 

0.87439 

74.40 

67.16 

58.73 

0.86778 

76  90 

69.95 

60,70 

0.86096 

79.40 

72.80    6 

0.87426 

74.45 

67.22 

58.77 

0.86764 

76.95 

70.01 

60.74 

0.86082 

79.45 

72.86    6 

0.87413 

74  50 

67.27 

58.81 

0.86751 

77  00 

70.06 

60.78 

0.86069 

79  50 

72.91    6 

0.87400 

74.55 

67.33 

58.85 

0,86737 

77  05 

70.12 

60.82 

0.86055 

79  55 

72.97    € 

0.87387 

74  60 

67.38 

58.89 

0,86724 

77.10 

70.18 

60.86 

0.86041 

79  60 

7.3.03    t 

0.87373 

74.65 

67.  U 

58.93 

0.86710 

77.15 

70.24 

60.90 

0.86027 

79.65 

73.09    i 

0.87360 

74.70 

67.49 

58.97 

0.86697 

77.20 

70.29 

60.94 

0.86013 

79.70 

73.14    f 

0.87347 

74.75 

67.55 

59.01 

0.86684 

77,25 

70.35 

60.98 

0.85999 

79  75 

73.20    ( 

0.87334 

74.80 

67.61 

59.04 

0.86671 

77,30 

70.40 

61.02 

0,85984 

79  80 

73.26    i 

0.87321 

74.85 

67.67 

59.08 

0,86657 

77.35 

70.46 

61.06 

0.85970 

79  85 

73.32    ( 

0.87308 

74.90 

67.72 

59.12 

0.86644 

77.40 

70.51 

61.10 

0.85956 

79.90 

73.37    { 

0.87295 

74.95 

67.78 

59.16 

0.86630 

77.45 

70.57 

61.14 

0.85942 

79.95 

73.43    ( 

0.87282 

75  00 

67.83 

59.20 

0,86617 

77.50 

70.63 

61.18 

0.85928 

80  00 

73.49    ( 

0.87269 

75  05 

67.89 

59.24 

0,86603 

77.55 

70.69 

61.22 

0.85914 

80  05 

73.55 

0.87256 

75  10 

67.94 

59.28 

0.86589 

77.60 

70.74 

61.25 

0.85901 

80.10 

73.60 

,0.87243 

75.15 

68.00 

59.32 

0.86575 

77,65 

70.80 

61.29- 

0.85887 

80.15 

73.66 

0.87230 

75  20 

68.05 

59.36 

0.86562 

77.70 

70.85 

61.33 

0.85873 

80.20 

73.72 

0.87217 

75  25 

68.11 

59.40 

0.86548 

77.75 

70.91 

61.37 

0.85859 

80.25 

73.78 

0.87204 

75  30 

68.16 

59.44 

0.86535 

77.80 

70.97 

61.41 

0.85846 

80  30 

73.83 

0.87190 

75  35 

68.22 

59,48 

0.86521 

77  85 

71.03 

61.45 

0.85832 

80  35 

73.89 

0.87177 

75.40 

68.27 

59.52 

0,86508 

77.90 

71.08 

61.49 

0.85818 

80  40 

73.95 

0.87164 

75.45 

68.33 

59.56 

0.86494 

77,95 

71.14 

61.53 

0.85804 

80.45 

74.01 

0.87151 

75.50 

68.38 

59.60 

0.86480 

78  00 

71.19 

61.57 

0.85789 

80  50 

7  4. 06 

0.87138 

75  55 

68.44 

59.64 

0.86466 

78  05 

71.25 

61.61 

0.85775 

80.55 

74.12 

0.87125 

75.60 

68.49 

59.67 

0.86453 

78  10 

71.31 

61.65 

0.85761 

80  60 

74. 18 

0.87111 

75  65 

68.55 

59.71 

0.86439 

78.15 

71.37 

61.69 

0.85747 

80  65 

74.24 

0.87098 

75  70 

68.60 

59.75 

0.86426 

78  20 

71.42 

61.73 

0.85733 

80.70 

74.30 

0.87084 

75.75 

68.66 

59.79 

0.86412 

78.25 

71.48 

61.77 

0.85719 

80.75 

74.36 

0.87071 

75.80 

68.72 

59.83 

0.86399 

78  30 

71.54 

61.81 

0.85705 

80  80 

74.42 

0.87058 

75.85 

68.78 

59.87 

0.86385 

78  35 

71.60 

61.85 

0.85691 

80  85 

74.48 

0.87045 

75.90 

68.83 

59,91 

0.86371 

78  40 

71.65 

61.88 

0.85677 

80  90 

74.53 

0.87032 

75.95 

68.89 

59.95 

0.86357 

78.45 

71.71 

61.92 

0.85663 

80  95 

74.59 

0.87019 

76.00 

68.94 

59.99 

0.86344 

78.50 

71.76 

61.96 

0.85648 

81  00 

74.65 

0.87005 

76  05 

69.00 

60.03 

0.86330 

78  55 

71.82 

62.00 

0.85634 

81.05 

74.71 

0.86992 

76  10 

69.05 

60.07 

0.86316 

78  60 

71.88 

62,04 

0.85620 

81.10 

74.77 

0.86979 

76.15 

69.11 

60.11 

0.86302 

78.65 

71.94 

62.08 

0.85606 

81.15 

74.83 

0.86966 

76  20 

69.16 

60.15 

0.86289 

78.70 

71.99 

62.12 

0.85592 

81.20 

74.88 

0.86952 

76.25 

69. 2i 

60.19 

0.86275 

78.75 

72.05 

62.16 

0.85578 

81.25 

74.94 

0.86939 

76  30 

69.27 

60.23 

0,86261 

78  80 

72.11 

62.20 

0.85564 

81.30 

75.00 

0.86925 

76  35 

69.35 

60.27 

0.86247 

78  85 

72.17 

62.24 

0.85550 

81  35 

75.06 

0.86912 

76.40 

69. 3S 

60.31 

0,86234 

78  90 

72.22 

62.28 

0.85536 

81.40 

75.12 

0.86898 

76.46 

69.4& 

60.35 

0,86220 

78.95 

72.28 

62.32 

0.85522 

81.45 

75.18 

0.86885 

76  50 

69.56 

60.39 

0,86206 

79  00 

72.34 

62.36 

0.85507 

81  50 

75.24 

0.86872 

76  55 

69.56 

60.43 

0,86192 

79.05 

72.40 

62.40 

0.85493 

81.55 

75.30 

0.86859 

76  60 

69.61 

60.47 

0.80179 

79.10 

72.45 

62.44 

0.85478 

81  60 

75.35 

0.86845 

76.65 

69.67 

60.51 

0.86165 

79.15 

72.51 

62.48 

0.85464 

81  65 

75.41 

0,86832 

76  70 

69.72 

60.54 

0.86151 

79.20 

72.57 

62.52 

0.85450 

81.70 

75.47 

XVI] 


WINES 


Table  16.— Alcohol  Table.— Continued. 


205 


t  BCIFIC 

ALCOHOL 

SPECIFIC 

ALCOHOL 

SPECIFIC 

A.LCOHOL 

AVITY 

)°C. 

Per  cent 

Per 

Grams 

°^o^c^ 

Per  cent 

Per 

Grams 

20°  C. 

Per  cent 

Per 

Grama 

1° 

by  volume 

cent  by 

per 

4° 

by  volume 

cent  by 

per 

4° 

by  volume|cent  by 

per 

at  20°C. 

weight 

100  cc. 

at  20°  C. 

weight 

100  cc. 

at  20°  C. 

weight 

100  cc. 

Cv>13G 

81  75 

75. 5S 

64.53 

0.84713 

84  26 

78.50 

66.50 

0.83957 

86  76 

81.56 

68.48 

055422 

81  80 

75.59 

64.57 

0.84698 

84  30 

78.56 

66.54 

0.83942 

86  80 

81.62 

68.52 

C5540S 

81  85 

75.65 

64.61 

0.84683 

84  36 

78.62 

66.58 

0.83927 

86  85 

81.68 

68.56 

(■;,-•!' i:{ 

81  90 

75.71 

64.65 

0.84668 

84.40 

78.68 

66.62 

0.83912 

86  90 

81.75 

68.60 

-  -'1 

81  95 

75.77 

64.69 

0.84654 

84.46 

78.74 

66.66 

0.83896 

86  96 

81.81 

68.64 

v,.,i,l 

82  00 

75.82 

64.73 

0.84639 

84  60 

78.80 

66.70 

0.83881 

87  00 

81.87 

68.68 

1  ^'.:;:,o 

82  05 

75.88 

64.77 

0.84624 

84.66 

78.86 

66.74 

0.83865 

87  05 

81.93 

68.72 

1  sXy.'A't 

82  10 

75.94 

64.81 

0.84609 

84.60 

78.93 

66.78 

0.83850 

87.10 

81.99 

68.76 

( vr):;_'2 

82  15 

76.00 

64.85 

0.84594 

84.66 

78.99 

66.82 

0.83834 

87.15 

82.05 

68.80 

1  vVinr 

82  20 

76.06 

64.88 

0.84579 

84.70 

79.05 

66.86 

0.83818 

87.20 

82.12 

68.84 

( vV_".>:; 

82  25 

76.12 

64.92 

0.84564 

84.76 

79.11 

66.90 

0.83802 

87.25 

82.18 

68.88 

(  vi_'7!t 

82  30 

76.18 

&4.96 

0.84549 

84  80 

79.17 

66.94 

0.83787 

87  30 

82.24 

68.91 

1   ^.' Jli.") 

82  35 

76.24 

65.00 

0.84534 

84.85 

79.23 

66.98 

0.83771 

87  36 

82.30 

68.95 

--      M) 

82  40 

76.30 

65.04 

0.84519 

84  90 

79.29 

67.02 

0.83756 

87.40 

82.37 

68.99 

.1-, 

82  46 

76.36 

65.08 

0.84504 

84.95 

79.35 

67.06 

0. 83740 

87  46 

82.43 

69.03 

('•;.3222 

82  50 

76.41 

65.12 

0.84489 

86.00 

79.41 

67.09 

0. 83725 

87  50 

82.49 

69.07 

(^207 

82  55 

76.47 

65.16 

0.84474 

86.06 

79.47 

67.13 

0.83709 

87  55 

82.55 

69.11 

mm 

82  60 

76.53 

65.20 

0.84459 

86.10 

79.53 

67.17 

0.83694 

87  60 

82.62 

69.15 

miTs 

82  65 

76.59 

65.24 

0.84444 

86  16 

79.59 

67.21 

0.83678 

87  65 

82.68 

69.19 

B5164 

82  70 

76.65 

65.28 

0.84429 

86  20 

79.65 

67.25 

0.83663 

87.70 

82.74 

69.23 

(v-.i:iO 

82  75 

76.71 

65.32 

0.84414 

85  25 

79.71 

67.29 

0.83647 

87  75 

82.80 

69.27 

( ^:,  1 :;.') 

82  80 

76.77 

65.36 

0.84399 

85.30 

79.78 

67.33 

0.83632 

87  80 

82.87 

69.30 

(<,5121 

82  85 

76.83 

65.40 

0.84384 

85  36 

79.84 

67.37 

0.83616 

87  85 

82.93 

69.34 

OS5106 

82  90 

76.89 

65.44 

0.84369 

86  40 

79.90 

67.41 

0.83601 

87  90 

82.99 

69.38 

(S5092 

82.95 

76.95 

65.48 

0.84354 

86.45 

79.96 

67.45 

0.83585 

87  95 

83.05 

69.42 

1  >;rii  )77 

83  00 

77.01 

65.51 

0.84339 

85  60 

80.02 

67.49 

0.83569 

88  00 

83.12 

69.46 

(-;.")i)(;;5 

83  05 

77.07 

65.55 

0.84323 

85  55 

80.08 

67.53 

0.83553 

88  06 

85.18 

69.50 

(85049 

83  10 

77.13 

65.59 

0.84308 

85  60 

80.14 

67.57 

0.83537 

88  10 

83.25 

69.54 

(?5n:]5 

83  15 

77.19 

65.63 

0.84293 

85.65 

80.20 

67.61 

0.83521 

88  15 

83.31 

69.58 

(<5()20 

83.20 

77.24 

65.67 

0.84278 

86  70 

80.27 

67.65 

0.83505 

88.20 

83.37 

69.62 

( s:,(  )i  IB 

83  26 

77.30 

65.71 

0.84263 

85  75 

80.33 

67.69 

0.83489 

88.26 

83.43 

69.66 

(.S49'.a 

83  30 

77.36 

65.75 

0.84248 

85  80 

80.39 

67.73 

0.83473 

88  30 

83.50 

69.70 

(84977 

83  35 

77.42 

65.79 

0.84?,S3 

86  86 

80.45 

67.77 

0.83457 

88  35 

83.56 

69.74 

(84902 

83  40 

77.48 

65.83 

0.84218 

85  90 

80.51 

67.80 

0.83442 

88  40 

83.65 

69.78 

(S4948 

83  45 

77.54 

65.87 

0.84203 

85  96 

80.57 

67.84 

0.83426 

88.45 

83.69 

69.82 

[■^I'l:]:] 

83  50 

77.60 

65.91 

0.84188 

86  00 

80.63 

67.88 

0.83410 

88  60 

83.75 

69.86 

■  'IS 

83  55 

77.66 

65.95 

0.84172 

86  06 

80.69 

67.92 

0.83394 

88  55 

83.81 

69.90 

i:-; 

83  60 

77.72 

65.99 

0.84157 

86  10 

80.76 

67.96 

0.83379 

88  60 

SS.88 

69.94 

^',t 

83  65 

77.78 

66.03 

0.84141 

86.15 

80.82 

68.00 

0.83363 

88  65 

83.94 

69.98 

^,^:4 

83  70 

77.84 

66.07 

0.84126 

86  20 

80.88 

68.04 

0.83347 

88.70 

8400 

70.01 

slvV.> 

83  75 

77.90 

66.11 

0.84110 

86  26 

SO.  94 

68.08 

0.8^331 

88  76 

84.06 

70.05 

MM4 

83  80 

77.96 

66.15 

0.84095 

86  30 

81.00 

68.12 

0.83315 

88  80 

84.15 

70.09 

sis:;() 

83  85 

78.02 

66.19 

0.84080 

86  36 

81.06 

68.16 

0.83290 

88  85 

84.19 

70.13 

Msi:> 

83  90 

78.08 

66.23 

0.ai065 

86  40 

81.13 

68.20 

0.832S3 

88  90 

84.26 

70.17 

MMll 

83  95 

78.14 

66.27 

0.84049 

86.46 

81.19 

68.24 

0.83267 

88  95 

84.32 

70.21 

S47St') 

84  00 

78.2C 

66.30 

0.84034 

86  60 

81.25 

68.28 

0.83251 

89  00 

84.39 

70.25 

184772 

84  05 

78.26 

66.34 

0.84018 

86  66 

81.31 

68.32 

0.83235 

89  05 

S4.4-5 

70.29 

181757 

84  10 

78.S& 

66.38 

0.84003 

86.60 

81.37 

68.36 

0.83219 

89  10 

84-51 

70.33 

V--J.J 

84.15 

78.3S 

66.42 

0.83987 

86  66 

81.43 

68.40 

0.83203 

89  15 

84.57 

70.37 

'27 

84.20 

78.4. 

66  46 

0.83972 

86  70 

81.50 

68.44 

0.S31S6 

89  20 

84.64 

70.41 

206 


METHODS    OF   ANALYSIS 


[Chap. 


5 

Table  16.— Alcohol  Table.- 

—Continued. 

SPECiric 

ALCOHOL 

SPECIFIC 

ALCOHOL 

SPECIFIC 

ALCOHOL 

GRAVITY 

20°  C. 

Per  cent 

Per 

Grams 

GRAVITY 
20°  C. 

Per  cent 

Per 

Grams 

'20°C. 

Per  cent 

Per 

Gran 

4° 

by  volume 

cent  by 

per 

4° 

by  volume 

cent  by 

per 

4° 

by  volume 

cent  by 

per 

at  20°  C. 

weight 

100  cc. 

at  20°  C. 

weight 

100  cc. 

at  20°  C. 

weight 

100  c( 

0.83170 

89  25 

8^.70 

70.45 

0,82332 

91  75 

87.96 

72.42 

0.81432 

94.25 

91.36 

74.4 

0.83154 

89  30 

84.77 

70.49 

0.82315 

91  80 

88.03 

72.46 

0.81413 

94.30 

91.43 

74.4 

0.83138 

89  35 

84.83 

70.53 

0.82298 

91  85 

88.09 

72.50 

0.81394 

94  35 

91.50 

74.4 

0.83121 

89  40 

84.90 

70,57 

0.82281 

91  90 

88.16 

72.54 

0.81375 

94.40 

91.57 

74.5 

0.83105 

89.45 

84.96 

70.61 

0,82263 

91.95 

88.22 

72.58 

0.81356 

94  45 

91.64 

74.5 

0.83089 

89  50 

85.03 

70.65 

0.82246 

92.00 

88.29 

72.62 

0.81337 

94.50 

91.71 

74.5 

0.83073 

89  55 

85.09 

70.69 

0.82229 

92  05 

88.36 

72,66 

0.81318 

94.55 

91.78 

74.6 

0.83056 

89  60 

85.15 

70.72 

0.82212 

92  10 

88.43 

72,70 

0.81299 

94  60 

91.85 

74.6 

0.83040 

89  65 

85.21 

70.76 

0.82194 

92.15 

88.49 

72.74 

0.81280 

94.65 

91.92 

74.7 

0.83024 

89  70 

85.28 

70.80 

0.82177 

92.20 

88.56 

72,78 

0.81260 

94.70 

91.99 

74.7 

0.83008 

89.75 

85.34 

70.84 

0.82159 

92  25 

88.63 

72,82 

0.81241 

94.75 

92.06 

74.7 

0.82991 

89  80 

85.41 

70.88 

0.82141 

92  30 

88.70 

72.86 

0.81222 

94  80 

92.13 

74.8 

0.82975 

89.85 

85.47 

70.92 

0.82123 

92  35 

88.76 

72.90 

0.81202 

94.85 

92.20 

74.8 

0.82958 

89  90 

85.54 

70.96 

0.82106 

92.40 

88.83 

72.94 

0.81183 

94.90 

92.27 

74.9 

0.82942 

89  95 

85.60 

71.00 

0.82088 

92  45 

88.89 

72.98 

0.81163 

94.95 

92.34 

74.9 

0.82925 

90  00 

85.67 

71,04 

0.82071 

92  50 

88.96 

73.02 

0.81144 

95.00 

92.41 

74.9 

0,82909 

90  05 

85.73 

71.08 

0,82053 

92  55 

89.03 

73.06 

0,81124 

95  05 

92.48 

75.0 

0.82892 

90  10 

85.80 

71.12 

0.82035 

92  60 

89.10 

73.09 

0,81105 

95.10 

92.55 

75.0 

0.82876 

90.15 

85.86 

71,16 

0.82017 

92  65 

89.16 

73.13 

0,81086 

95.15 

92.63 

75.1 

0.82859 

90  20 

85.93 

71.20 

0.82000 

92.70 

89.23 

73.17 

0.81067 

95.20 

92.70 

75.1 

0.82843 

90  25 

85.99 

71.24 

0.81982 

92  75 

89.30 

73.21 

0.81047 

95  25 

92.77 

75.1 

0.82826 

90  30 

86.06 

71,28 

0.81964 

92  80 

89.37 

73.25 

0.81028 

95  30 

92.84 

75.2 

0.82810 

90  35 

86.12 

71,32 

0.81946 

92  85 

89.43 

73.29 

0.81008 

95.35 

92.91 

75.2 

0.82793 

90  40 

86.19 

71,36 

0.81929 

92,90 

89.50 

73.33 

0.80988 

95  40 

92.98 

75.3 

0.82776 

90  45 

86.25 

71.40 

0.81911 

92  95 

89.57 

73.37 

0.80968 

95  45 

93.05 

75.3 

0.82759 

90  50 

86.32 

71,44 

0.81893 

93  00 

89.64 

73.41 

0.80949 

95.50 

93.12 

75.3 

0.82742 

90  55 

86.38 

71,48 

0.81875 

93  05 

89.71 

73.45 

0.80929 

95  55 

93.20 

75.4 

0.82725 

90  60 

86.45 

71,52 

0,81856 

93  10 

89.78 

73.49 

0.80909 

95.60 

93.27 

75.4 

0.82708 

90  65 

86.51 

71,56 

0,81838 

93  15 

89.84 

73.53 

0.80889 

95  65 

93.34 

75.5 

0.82691 

90.70 

86.58 

71,59 

0,81821 

93  20 

89.91 

73.57 

0.80869 

95.70 

93.41 

75.5 

0.82674 

90  75 

86.64 

71,63 

0.81803 

93  25 

89.98 

73.61 

0.80849 

95.75 

93.48 

75.5 

0.82657 

90  80 

86.71 

71.67 

0.81784 

93  30 

90.05 

73.65 

0.80829 

95  80 

93.55 

75.6 

0.82640 

90  85 

86.77 

71.71 

0.81766 

93  35 

90.12 

73.69 

0.80809 

95  85 

93.63 

75.6 

0.82624 

90  90 

86.84 

71.75 

0.81748 

93  40 

90.19 

73.72 

0.80789 

95  90 

93.70 

75.7 

0.82607 

90  95 

86.90 

71.79 

0.81730 

93,45 

90.25 

73.76 

0.80769 

95.95 

93.77 

75.7 

0.82590 

91  00 

86.97 

71.83 

0,81711 

93  50 

90.32 

73,80 

0.80749 

96  00 

93.84 

75.7 

0.82573 

91.05 

87.03 

71.87 

0,81693 

93  55 

90.39 

73.84 

0.80729 

96  05 

93.92 

75.8 

0.82556 

91  10 

87.10 

71,91 

0,81675 

93  60 

90.46 

73,88 

0.80709 

96.10 

93.99 

75.8 

0.82539 

91  15 

87.17 

71,95 

0,81657 

93  65 

90.53 

73.92 

0,80689 

96.15 

94.06 

75.9 

0.82522 

91  20 

87.24 

71,99 

0.81638. 

93  70 

90.60 

73.96 

0,80668 

96.20 

94.13 

75.9 

0.82505 

91  25 

87.30 

72.03 

0.81620 

93  75 

90.67 

74,00 

0,80648 

96.25 

94.21 

75.9 

0.82488 

91  30 

87.37 

72,07 

0.81601 

93  80 

90.74 

74,04 

0,80627 

96  30 

94.28 

76.0 

0.82470 

91.35 

87.43 

72,11 

0.81582 

93,85 

90.80 

74.08 

0.80607 

96.35 

94.35 

76.0 

0.82453 

91  40 

87.50 

72,15 

0,81563 

93,90 

90.87 

74,12 

0.80586 

96.40 

94.42 

76.0 

0.82436 

91.45 

87.56 

72,19 

0,81545 

93,95 

90.94 

74,16 

0.80566 

96.45 

94.50 

76.1 

0.82419 

91  50 

87.63 

72,23 

0.81526 

94  00 

91.01 

74.20 

0.80545 

96.50 

94.57 

76.1 

0.82401 

91  55 

87.69 

72,27 

0.81507 

94,05 

91.08 

74.24 

0.80525 

96  55 

94.65 

76.2 

0.82384 

91  60 

87.76 

72,30 

0.81488 

94,10 

91.15 

74.28 

0.80504 

96  60 

94.72 

76.2 

0.82367 

91  65 

87.83 

72.34 

0.81469 

94,15 

91.22 

74.32 

0.80483 

96  65 

94.79 

76.2 

0.82350 

91  70 

87.90 

72.38 

0.81450 

94,20 

91.29 

74.36 

0.80462 

98  70 

94.86 

76.3 

XVI] 

• 

WINES 

207 

Table  16.— Alcohol  1 

^ABLE.- 

-Concluded. 

HviTT 

ALCOHOL 

SPECIFIC 

ALCOHOL 

SPECIFIC 

ALCOHOL 

Per  cent 

Per 

Grams 

20°  C. 

Per  cent 

Per 

Grams 

GRAVITY 
20°  C. 

Per  cent 

Per 

Grams 

lit" 

by  volume 

cent  by 

per 

4° 

by  volume  cent  by 

per 

4° 

by  volume  cent  by 

per 

11 

at  20°  C. 

weight 

100  cc. 

at  20°  C. 

weight 

100  cc. 

at  20°  C. 

weight 

100  cc. 

llo442 

96  75 

94.94 

76.37 

0.79900 

98  00 

96.82 

77.36 

0.79311 

99  25 

98.78 

78.34 

o;o42i 

96  80 

95.01 

76.41 

0.79878 

98  05 

96.90 

77.40 

0.79286 

99  30 

98.86 

78.38 

010400 

96  85 

95.09 

76.45 

0.79855 

98  10 

96.97 

77.43 

0.79262 

99  35 

98.94 

78.42 

'>;i),'^7<t 

96  90 

95.16 

76.49 

0.79832 

98  15 

97.05 

77.47 

0.79237 

99.40 

99.02 

78.46 

Vs 

96  95 

95.24 

76.53 

0.79809 

98  20 

97.12 

77.51 

0.79213 

99  45 

99.10 

78.50 

n:„;7 

97  00 

95.31 

76.57 

0.79786 

98  25 

97.20 

77.55 

0.79188 

99  50 

99.18 

78.54 

u;;i."i 

97,05 

95.39 

76.61 

0.79763 

98.30 

97.28 

77.59 

0.79163 

99  55 

99.26 

78.58 

():_"•  1 

97  10 

95.46 

76.65 

0,79740 

98  35 

97.36 

77.63 

0.79138 

99  60 

99.34 

78.62 

■;::; 

97  15 

95.53 

76.69 

0.79717 

98.40 

97.43 

77.67 

0.79113 

99  65 

99.42 

78.66 

-' 

97.20 

95.60 

76.72 

0.79695 

98  45 

97.51 

77.71 

0.79088 

99.70 

99.51 

78.70 

::) 

97  25 

95.68 

76.76 

0.79672 

98  50 

97.59 

77.75 

0.79062 

99  75 

99.59 

78.74 

N 

97  30 

95.75 

76.80 

0.79648 

98.56 

97.67 

77.79 

0.79037 

99  80 

99.67 

78.78 

('1  m; 

97  35 

95.83 

76.84 

0.79625 

98.60 

97.75 

77.83 

0.79011 

99  85 

99.75 

78.82 

0  01G4 

97  40 

95.91 

76.88 

0.79601 

98.65 

97.83 

77.87 

0.78986 

99  90 

99.83 

78.86 

0'0143 

97.45 

95.98 

76.92 

0.79577 

98.70 

97.90 

77.91 

0.78960 

99  96 

99.91 

78.90 

0  0122 

97  50 

96.05 

76.96 

0.79553 

98  75 

97.98 

77.95 

0.78934 

100  00 

100.00 

78.93 

0  0100 

97  55 

96.13 

77.00 

0.79529 

98  80 

98.06 

77.99 

0  0l)7S 

97  60 

96.21 

77.04 

0.79505 

98  85 

98.14 

78.03 

i)n:,C) 

97.65 

96.29 

77.08 

0.79481 

98.90 

98.22 

78.07 

'i\n:,[ 

97.70 

96.36 

77.12 

0.79457 

98  95 

98.30 

78.11 

97  75 

96.44 

77.16 

0.79432 

99  00 

98.38 

78.14 

'    i  ) 

97  80 

96.52 

77.20 

0.79408 

99  05 

98.46 

78.18 

'  .t'.liiS 

97.85 

96.60 

77.24 

0.79384 

99  10 

98.54 

78.22 

)  ,t'.>l5 

97  90 

96.68 

77.28 

0.79360 

99  15 

98.62 

78.26 

)  i',L':; 

97  95 

96.75 

77.32 

0.70335 

99  20 

98.70 

78.30 

208 


METHODS    OF   ANALYSIS 


[Chap. 


Table  17.— Alcoh| 
For  calculating  the  percentages  of  alcohol  in  mixtures  of  ethyl  alcohol  a 


Per  cent 

by 
volume 


Per  cent 

by 
weight 


Per  cent 

by 
volume 


Per  cent 

by 
weight 


Per  cent 

by 
volume 


Per  cent 

by 
weight 


Per  cent 

by 
volume 


13.2 
13.3 
13.4 

13.5 
13.6 
13,7 
13.8 
13.9 

14.0 
14.1 
14.2 
14.3 
14.4 

14.5 
14.6 
14.7 
14.8 
14.9 

15.0 
15.1 
15.2 
15.3 
15.4 

15.5 
15.6 
15.7 
15.8 
15.9 

16.0 
16.1 
16.2 
16.3 
16.4 

16.5 
16.6 
16.7 
16.8 
16.9 

17.0 
17.1 
17.2 
17.3 
17.4 

17.5 
17.6 
17.7 
17.8 
17.9 


0  00 

0  09 
0.17 
0.26 
0.34 

0.43 
0.51 
0.59 
0.68 
0.76 

0.84 
0.93 

1  02 
1  10 
1.18 

1.26 
1  34 
1.41 
1.49 
1.66 


2,00 
2.07 
2.14 
2.21 
2.29 


0.00 
0.07 
0.13 
0.20 
0.27 

0.84- 
0.40 
0.47 
0.54 
0.60 

0.67 
0.74 
0.81 
0.87 
0.94 

1.00 
1.06 
1.12 
1.18 
1.24 

1.30 
1.35 
1.41 
1.47 
1.53 

1.69 
1.65 
1.70 
1.76 
1.82 


0  10 
0  19 
0.27 
0  36 
0.44 

0.53 
0.60 
0.69 
0.78 

0  85 

0.94 
1.03 
1.12 

1  19 
1.29 

1.36 
1.43 
1  50 
1.57 
1  65 

1.72 
1.80 
1.87 
1.94 
2.01 

2.09 
2.16 
2.24 
2.31 
2.38 


0.01        0.01 


0.08 
0.15 
0.21 
0.28 
0.35 

0.42 
0.48 
0.55 
0.62 
0.68 

0.75 
0.82 
0.89 
0.95 
1.02 

1.08 
1.13 
1.19 
1.25 
1.31 

1.37 
1.43 
1.49 
1.54 
1.60 

1.66 
1.72 
1.78 
1.84 
1.89 


0  05 
0.14 
0  23 

0  31 
0  39 
0.48 
0  57 
0.66 

0.73 
0.82 
0.91 

0  99 
1.08 

1.17 
1.24 
1.32 
1.40 
1.47 

1  65 
1.62 
1.70 
1.77 
1.85 

1.92 
1.99 
2.06 
2.14 
2.21 

2.29 

2  36 
2,44 
2  61 
2.69 


0.04 

0.11 
0.18 

0.24 
0.31 
0.38 
0.45 
0.51 

0.58 
0.65 
0.72 
0.79 
0.86 

0.93 
0.99 
1.05 
1.11 
1.17 

1.23 
1.29 
1.35 
1.41 
1.47 

1.53 
1.58 
1.64 
1.70 
1.76 

1.88 
1.94 
2.00 
2.06 


0  08 
0.16 
0.26 
0.34 
0.43 

0.62 
0  60 

0  69 
0.77 
0.86 

0.94 
1.03 
1.12 
1.21 
1.28 

1.36 
1.44 
1.61 
1.69 
1.66 

1.74 
1.81 
1.89 

1  96 
2.04 

2.11 
2.19 
2.26 

2  34 
2.41 

2.49 
2.66 
2.62 
2.70 
2.77 


•  Calculated  and  arranged  by  B.  H.  St.  John  from  the  data  of  Boroshevskii  and  Dvorzhanchik.^ 


XVI] 


Table. 

water  from  their  Zei^s  immersion  refractometer  readings*  at  17.5°-25°C. 


209 
6 


2rc. 

22° 

c. 

23 

c. 

24 

C. 

25° 

c. 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

SCALE 
READINQ 

by 

by 

by 

by 

by 

by 

by 

by 

by 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

0.00 

0.00 

13.2 

0  09 

0.07 

13.3 

0.18 

0.14 

13.4 

0  05 

0.04 

0.26 

0.21 

13.5 

0.14 

0.11 

0  36 

0.28 

13.6 

0  01 

0.01 

0  23 

0.18 

0  44 

0.35 

13.7 

0  10 

0.08 

0  31 

0.25 

0.63 

0.42 

13.8 

0  19 

0.15 

0  40 

0.32 

0.62 

0.49 

13.9 

0  08 

0.06 

0.28 

0.22 

0  49 

0.39 

0.70 

0.56 

14.0 

0  16 

0.13 

0  36 

0.29 

0  58 

0.46 

0.79 

0.63 

14.1 

o'.os 

0  24 

0.19 

045 

0.36 

0  67 

0.53 

0  88 

0.70 

14.2 

0.10 

0  33 

0.26 

0  54 

0.43 

0.75 

0.60 

0.97 

0.77 

14.3 

0.17 

0.41 

0.33 

0  63 

0.50 

0.84 

0.67 

1.06 

0.85 

14.4 

0.23 

0  50 

0.40 

0.72 

0.57 

0  93 

0.74 

1.15 

0.92 

14.5 

O.SO 

0.59 

0.47 

0.80 

0.64 

1.02 

0.81 

1  24 

0.99 

14.6 

0.37 

0  68 

0.64 

0.89 

0.71 

1.11 

0.88 

1  32 

1.05 

14.7 

0.44 

0  77 

0.61 

0.98 

0.78 

1  19 

0.95 

1.40 

1.11 

14.8 

0.51 

0  86 

0.68 

1.07 

0.85 

1.28 

1.02 

1.47 

1.17 

14.9 

0.58 

0.94 

0.75 

1.16 

0.92 

1.36 

1.08 

1.66 

1.23 

15.0 

0.65 

1  03 

0.82 

1.24 

0.99 

1.44 

1.14 

1.63 

1.29 

15.1 

0.72 

1  12 

0.89 

1.32 

1.05 

1.61 

1.20 

1.71 

1.36 

15.2 

0.79 

1.21 

0.96 

1.40 

1.11 

1.59 

1.26 

1.79 

1.42 

15.3 

0.85 

1.29 

1.02 

1.47 

1.17 

1.66 

1.32 

1.86 

1.48 

15.4 

0.92 

1  36 

1.08 

1.55 

1.23 

1.74 

1.S8 

1.94 

1.54 

15.5 

0.99 

1.44 

1.15 

1  62 

1.29 

1.82 

1-44 

2.01 

1.60 

15.6 

1.05 

1.52 

1.21 

1.70 

1.35 

1.90 

1.51 

2.09 

1.66 

15.7 

1.11 

1.60 

1.27 

1.77 

1.41 

1.97 

1.67 

2.17 

1.72 

15.8 

1.17 

1.67 

l.SS 

1.86 

1.47 

2.06 

1.63 

2.26 

1.79 

15.9 

1.23 

1.75 

1.39 

1.92 

1.53 

2  12 

1.69 

2  33 

1.85 

16.0 

1.29 

1.82 

1.45 

2.00 

1.59 

2.20 

1.75 

2.40 

1.91 

16.1 

1.35 

1  90 

1.51 

2.08 

1.65 

2.27 

1.81 

2.48 

1.97 

16.2 

1.41 

1.97 

1.57 

2.16 

1.72 

2.36 

1.87 

2  66 

2.05 

16.3 

1.47 

2  05 

1.63 

2.24 

1.78 

2.43 

1.93 

2.62 

2.09 

16.4 

1.53 

2.12 

1.69 

2.31 

1.84 

2  50 

1.99 

2.70 

2.15 

16.5 

1.59 

2.20 

1.75 

2  39 

1.90 

2  57 

2.05 

2.77 

2.21 

16.6 

1.65 

2.27 

1.81 

2.46 

1.96 

2  65 

2.11 

2  86 

2.27 

16.7 

1.71 

2  36 

1.87 

2.53 

2.02 

2  72 

2.17 

2  92 

2.33 

16.8 

1.77 

2.43 

1.93 

2.61 

2.08 

2.80 

2.23 

2.99 

2.38 

16.9 

1.83 

2.60 

1.99 

2.69 

2.14 

2.87 

2.29 

3  06 

2.44 

17.0 

1.89 

2.67 

2.05 

2  76 

2.20 

2.96 

2.36 

3.14 

2.60 

17.1 

1.95 

2  65 

2.11 

2  82 

2.25 

3  02 

2.41 

3  21 

2.66 

17.2 

2.01 

2.72 

2.17 

2.90 

2.31 

3.10 

2.47 

3.29 

2.62 

17.3 

2.07 

2.79 

2.23 

2.97 

2.37 

3.17 

2.63 

3.36 

2.68 

17.4 

2.12 

2.86 

2.28 

3.04 

2.43 

3  26 

2.59 

3.43 

2.74 

17.5 

2.18 

2  94 

2.34 

3  12 

2.49 

3  32 

2.65 

3  61 

2.80 

17.6 

2.24 

3.01 

2.40 

3  20 

2.55 

3  39 

2.70 

3  68 

2.86 

17.7 

2.30 

3.09 

2.46 

3.27 

2.61 

3  46 

2.76 

3  66 

2.92 

17.8 

2.36 

3.16 

2.52 

3.35 

2.67 

3  53 

2.82 

3.73 

2.98 

17.9 

210 

METHODS    OF    ANALYSIS 

[Chap. 

6 

Table  17.- 

-Alcoho 

17.5 

°c. 

18° 

C. 

19° 

c. 

20° 

c. 

21°  C. 

SCALE 
BEADING 

Per  cent 

Per  cont 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

by 

by 

by 

by 

by 

by 

by 

by 

by 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

18.0 

2.36 

1.88 

2  45 

1.95 

2.66 

2.12 

2.85 

2.27 

3.04 

18.1 

2  43 

l.H 

2  52 

2.01 

2.74 

2.18 

2  92 

2.33 

3.11 

18.2 

2.50 

2.00 

2.60 

2.07 

2.81 

2.24 

3.00 

2.39 

3  19 

18.3 

2.57 

2.05 

2.67 

2.13 

2.89 

2.30 

3.07 

2.45 

3  26 

18.4 

2.65 

2.11 

2.75 

2.19 

2.96 

2.36 

3.15 

2.51 

3.34 

18.5 

2.72 

2.17 

2  82 

2.25 

3  03 

2.41 

3  22 

2.57 

3.41 

18.6 

2  80 

2.23 

2.90 

2.31 

3.10 

2.47 

3  30 

2.63 

3  48 

18.7 

2.87 

2.29 

2  97 

2.37 

3.17 

2.53 

3  37 

2.69 

3  55 

18.8 

2  95 

2.35 

3  05 

2.43 

3  25 

2.59 

3  45 

2.75 

363 

18.9 

3.02 

2.41 

3.12 

2.49 

3  32 

2.65 

3  52 

2.81 

3  70 

19.0 

3  10 

2.47 

3  19 

2.54 

3  40 

2.71 

3  59 

2.86 

377 

19.1 

3  17 

2.53 

3  26 

2.60 

3.47 

2.77 

3  66 

2.92 

3  85 

19.2 

3  25 

2.59 

3.34 

2.66 

3  55 

2.83 

3  73 

2.98 

3  92 

19.3 

3  32 

2.65 

3.41 

2.72 

3  62 

2.89 

3  81 

3.04 

4  00 

19.4 

3  39 

2.70 

3  48 

2.78 

3  70 

2.95 

3.88 

3.10 

4.07 

19.5 

3  46 

2.76 

3  56 

2.84 

3  77 

3.01 

3  96 

3.16 

4.14 

19.6 

3  53 

2.82 

3  63 

2.90 

3,84 

3.06 

4  03 

3.22 

4  22 

19.7 

3  61 

2.88 

3.71 

2.96 

3.91 

3.12 

4.10 

3.27 

4.29 

19.8 

3  68 

2.94 

3  78 

3.02 

3.98 

3.18 

4.17 

3.33 

4  37 

19.9 

3  76 

3.00 

3  86 

3.08 

4.06 

3.24 

4.25 

3.39 

4.44 

20.0 

3  83 

3.08 

3  93 

3.13 

4.13 

3.30 

4  32 

3.45 

4.52 

20.1 

3.90 

3.12 

4  00 

3.19 

4.20 

3.35 

4  39 

3.51 

4  59 

20.2 

3  97 

3.17 

4  07 

3.25 

4.27 

3.41 

4.47 

3.57 

4  66 

20.3 

4.04 

3.23 

4  14 

3.31 

4.34 

3.47 

4  54 

3.63 

4.74 

20.4 

4.12 

3.29 

4  22 

3.37 

4.42 

3.53 

4.61 

3.68 

4  82 

20.5 

4.19 

3.35 

4.29 

3.43 

4.49 

3.59 

4.68 

S.74 

4.89 

20.6 

4.26 

3.41 

4  36 

3.49 

4.56 

3.65 

4.75 

3.80 

4  96 

20.7 

4  33 

3.46 

4.43 

3.54 

4.63 

3.70 

4  83 

3.86 

6  03 

20.8 

4.41 

3.52 

4  51 

3.60 

4  70 

3.76 

4  90 

3.92 

5  10 

20.9 

4.48 

3.58 

4.58 

3.66 

4.78 

3.82 

4.97 

3.98 

5.17 

21.0 

4.56 

3.64 

4  65 

3.72 

4  85 

3.88 

5.04 

4.03 

5.24 

21.1 

4  63 

3.70 

4.73 

3.78 

4.92 

3.94 

5.11 

4.09 

5  31 

21.2 

4  70 

3.76 

4  80 

3.84 

4.99 

3.99 

5  19 

4.15 

5  39 

21.3 

4.77 

3.81 

4  87 

3.89 

5  06 

4.05 

5  26 

4.21 

5.46 

21.4 

4.84 

3.87 

4.94 

3.95 

5.14 

4.11 

5  33 

4.26 

5.53 

21.5 

4.92 

3.93 

5  01 

4.01 

5  21 

4.17 

5.40 

4.32 

5  60 

21.6 

4  99 

3.99 

5  09 

4.07 

5  28 

4.22 

5.47 

4.38 

5.67 

21.7 

5  06 

4.05 

5.16 

4.13 

5  35 

4.28 

5.54 

4.U 

5.75 

21.8 

5  13 

4.10 

5  23 

4.18 

5  43 

4.34 

5.61 

4.49 

5  82 

21.9 

5.20 

4.16 

5  30 

4-24 

5.50 

4-40 

5  69 

4.55 

5.89 

22.0 

5.27 

4.22 

5  37 

4.30 

5.57 

4-45 

5  76 

4.61 

5.96    P 

22.1 

5.34 

4.27 

5.44 

4.35 

5.64 

4.51 

5.83 

4.67 

6  03 

22.2 

6.41 

4.33 

5  51 

4-41 

5.71 

4.57 

5.90 

4.72 

6.11 

22.3 

5.49 

4.39 

5.58 

4-47 

5.78 

4.63 

5.97 

4.78 

6.18 

22.4 

5.56 

445 

5.65 

4.53 

5.85 

4.68 

6.05 

h-84 

6.25 

22.5 

5.63 

4.51 

5.72 

4.58 

5.92 

4.74 

6.12 

4.90 

6  32 

22.6 

5.70 

4.56 

5.80 

4-64 

6.00 

4.80 

6.19 

4.95 

6  39 

22.7 

5.77 

4.62 

5.87 

4.70 

6.07 

4.86 

6  26 

5.01 

6  46 

22.8 

5.85 

4.68 

5.94 

4.75 

6.14 

4.91 

6.33 

5.07 

6  53 

22.9 

5  92 

474 

6  01 

4.81 

6.21 

4.97 

6.40 

5.13 

6  60 

XVI] 


WINES 


211 


Fable.- 

-Continued. 

( 

21°  C. 

22°  C. 

23° 

C. 

24° 

C. 

25° 

c. 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

SCALE 
READING 

by 

by 

by 

by 

by 

by 

by 

by 

by 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

2.42 

3.23        2.58 

3  42 

2.73 

3  61 

2.88 

3  81 

S.O4 

18.0 

248 

3  30        2.63 

3  50 

2.79 

3.68 

2.94 

3  88 

3.10 

18.1 

2.54 

3.37        2.69 

3  57 

2.85 

3  76 

3.00 

3  96 

3.16 

18.2 

2.60 

3.45         2.75 

3.64 

2.91 

3  83 

3.06 

4  03 

3.22 

18.3 

2.66 

3.52        2.81 

3  71 

2.96 

3  91 

3.12 

4.11 

3.28 

18.4 

2.72 

3.59        2.87 

3.78 

3.02 

3  98 

3.18 

4.18 

3.34 

18.5 

2.78 

3.66        2.92 

3.86 

3.08 

4.06 

3.24 

4.26 

3. 40 

18.6 

2.83 

3.73        2.98 

3  93 

3.14 

4.13 

3.30 

4  33 

3.46 

18.7 

2.89 

3.81        3.04 

4.01 

3.20 

4.21 

3.36 

4  41 

3.52 

18.8 

2.95 

3.88        3.10 

4.08 

3.26 

4  28 

3.42 

4.48 

3.58 

18.9 

3.01 

3.96        3.16 

4.16 

3.32 

4.36 

3.48 

4.56 

3.64 

19.0 

3.07 

4.03        3.22 

4  23 

3.38 

4.43 

3.54 

4.63 

3.70 

19.1 

3. IS 

4.11        3.28 

4  31 

3.44 

4.51 

3.60 

4.70 

3.76 

19.2 

3.19 

4.18        3.34 

4.38 

3.60 

4.58 

3.66 

4.78 

3.82 

19.3 

3.25 

4.26        S.40 

4.46 

3.66 

4.65 

3.72 

4.85 

3.88 

19.4 

3. 31 

4.33        3.46 

4.53 

3.62 

4.73 

3.78 

4.93 

3.94 

19.5 

3.37 

4.41        3.52 

4.61 

3.68 

4.80 

3.84 

5.00 

4.00 

19.6 

3.43 

4.48        3.58 

4.68 

3.74 

4.88 

3.90 

5  08 

4.06 

19.7 

3.49 

4.56        3.64 

4.75 

3.80 

4  95 

3.96 

5.15 

4.12 

19.8 

3.65 

4.63        3.70 

4.83 

3.86 

6  03 

4.02 

5.22 

4.17 

19.9 

3.61 

4.72        3.77 

4.90 

3.92 

5.10 

4.08 

5.29 

4.23 

20.0 

3.67 

4.79        3. 83 

4.98 

3.98 

5.17 

4.13 

6.36 

4.29 

20.1 

3.73 

4.87        3.89 

5  05 

4.04 

5  24 

4.19 

5.44 

4.36 

20.2 

3.79 

4.94        3.95 

5  13 

4.10 

531 

4.25 

5  51 

4-41 

20.3 

3.85 

5.01        401 

5  20 

4.16 

5  38 

4.31 

5.58 

4.47 

20.4 

3.91 

5.08        4-06 

5  27 

4.21 

5  45 

4.37 

5  65 

4.62 

20.5 

3.97 

5.15        4-12 

5  34 

4.27 

5.52 

4.42 

5  72 

4.68 

20.6 

4.02 

5.22        4-18 

5.41 

4.33 

5.60 

4-48 

5.80 

4.64 

20.7 

4.O8 

5.29        .^.^4 

5.48 

4.39 

5.67 

4.64 

5.87 

4.70 

20.8 

4.14 

5.36        4.^9 

5.55 

4-45 

5.75 

4. 60 

5.95 

4.76 

20.9 

4.20 

5.44        4.35 

5.62 

4.50 

5.82 

4.66 

6.02 

4.81 

21.0 

4.25 

5.51        4.4^ 

5.70 

4.56 

5.89 

4.72 

6.09 

4.87 

21.1 

4.31 

5.58        4-47 

5.77 

4.62 

5  96 

4.77 

6.16 

4.93 

21.2 

4.37 

5.65        4.5^ 

5.84 

4.68 

6.03 

4.83 

6  23 

4.99 

21.3 

4.43 

5.72        4.5S 

5.91 

4.73 

6.11 

4.89 

6.30 

5.06 

21.4 

4-48 

5.80        4.64 

5.98 

4.79 

6.18 

4.95 

6.37 

5.10 

21.5 

4.54 

5.87        4.70 

6.06 

4.85 

6  25 

5.01 

6.44 

5.16 

21.6 

4.60 

5.94        4.75 

6.13 

4.91 

6  32 

5.06 

6.52 

6.22 

21.7 

4.66 

6.01        4.8^ 

6.20 

4.97 

6.39 

5.12 

6.59 

6.28 

21.8 

4.71 

6.08        4.S7 

6  27 

5.02 

6.47 

5.18 

6.66 

5.34 

21.9 

4.77 

6.15        4.93 

6  34 

5.0s 

6.54 

5.24 

6.73 

5.39 

22.0 

4.83 

6.22        4.5S 

6.42 

5.14 

6.61 

6.29 

6.80 

5.46 

22.1 

4.89 

6.29        5.04 

6.49 

5.20 

6.68 

6.35 

6  87 

6.61 

22  2 

4.95 

6.36        5.70 

6.56 

5.25 

6.75 

6.41 

6.94 

5.67 

22^3 

5.00 

6.43        5.;5 

6.63 

5. 31 

6.82 

5.47 

7.01 

5.62 

22.4 

5.06 

6.50        5.21 

6.70 

5.37 

6.89 

5.52 

7.08 

6.68 

22.5 

6.11 

6.57        5.57 

6.77 

5.43 

6.96 

6.68 

7.16 

5.74 

22.6 

5.17 

6.64        5.33 

6.84 

5.48 

7.03 

5.64 

7.23 

6.80 

22.7 

6.28 

6.71         5.38 

6  91 

5.54 

7.10 

5.70 

7.31 

5.86 

22.8 

6.29 

6.78        5.44 

6.99 

5.60 

7.17 

5.75 

7.38 

5.91      1 

22.9 

212 
6 


METHODS    OF   ANALYSIS 


[Chap. 


Table  17.— Alcoho 


17.5 

'  c. 

18° 

C. 

19° 

C. 

20° 

C 

21°  C. 

SCALE 

READING 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

by 

by 

by 

by 

by 

by 

by 

by 

by 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

23.0 

5  99 

4.75 

6.08 

4.87 

6  28 

5.03 

6.47 

5.18 

6.67 

23.1 

6  06 

A.85 

6.15 

4.93 

6  35 

5.09 

6  54 

5.24 

6.74 

23.2 

6  13 

4.91 

6.22 

4.98 

6  42 

5.14 

6  61 

5.30 

6.81 

23.3 

6.20 

4.97 

6  29 

5.04 

6.49 

5.20 

6.68 

5.36 

6.88 

23.4 

6.27 

5.02 

6  36 

5.10 

6  56 

5.26 

6.75 

5.41 

6.95 

23.5 

6  34 

5.08 

6  43 

5.15 

6  63 

5.31 

6.83 

5  47 

7.02 

23.6 

6  41 

5.14 

6  50 

5.21 

6  70 

5.37 

690 

5.53 

7.09 

23.7 

6  48 

5.19 

6  57 

5.27 

6  78 

5.43 

6  97 

5.59 

7  16 

23.8 

6  55 

5.25 

6  64 

5.32 

6.85 

5.49 

7  04 

5.64 

7.23 

23.9 

6.62 

5.30 

6.71 

5.38 

6.92 

5.54 

7  11 

5.70 

7  31 

24.0 

6  69 

5.36 

6  78 

5.44 

6.99 

5.60 

7  18 

5.76 

7.38 

24.1 

6  76 

5.42 

6  85 

5.49 

7  06 

5.66 

7.26 

5.82 

7.45 

24.2 

6  83 

5.47 

6  92 

5.55 

7.13 

5.71 

7  32 

5.87 

7.62 

24.3 

6  90 

5.53 

6  99 

5.61 

7  20 

5.77 

7  39 

5.93 

7.59 

24.4 

6  97 

5.59 

7.06 

5.66 

7.27 

5.83 

7.46 

5.99 

7  66 

24.5 

7.04 

5.64 

7.13 

5.72 

7.34 

5.89 

7  53 

6.04 

7.73 

24.6 

7  11 

5.70 

7  20 

5.78 

7.41 

5.94 

7.60 

6.10 

7  80 

24.7 

7.18 

5.76 

7.27 

5.83 

7.48 

6.00 

7.67 

6.15 

7  86 

24.8 

7.25 

5.81 

7.35 

5.89 

7  55 

6.06 

7.74 

6.21 

7  93 

24.9 

7  32 

5.87 

7.42 

5.95 

7  62 

6.11 

7.81 

6.26 

800 

25.0 

7.39 

5.93 

7  49 

6.01 

7.68 

6.16 

7  88 

6.32 

8.06 

25.1 

7  46 

5.98 

7.56 

6.06 

7.75 

6.22 

7.94 

6.37 

8.13 

25.2 

7  53 

6.04 

7  63 

6.12 

7  82 

6.27 

8  01 

6.43 

8  20 

25.3 

7  59 

6.09 

7  69 

6.17 

7  89 

6.33 

8  07 

6.48 

8.27 

25.4 

7.66 

6.15 

7.76 

6.23 

7  95 

6.38 

8  14 

6.54 

8.34 

25.5 

7.73 

6.20 

7  83 

6.28 

8  02 

6.44 

8.21 

6.59 

8.41 

25.6 

7  80 

6.26 

7  90 

6.34 

8  09 

6.49 

8  28 

6.65 

8.48 

25.7 

7  87 

6.31 

7  96 

6.39 

8  16 

6.55 

8  35 

6.70 

8  55 

25.8 

7.94 

6.37 

8  03 

6.44 

8  22 

6.60 

8.42 

6.76 

8.62 

25.9 

8  00 

6.42 

8  10 

6.50 

8.29 

6.66 

8  48 

6.81 

8.69 

26.0 

8  07 

6.48 

8.16 

6.55 

8  36 

6.71 

8  55 

6.87 

8.75 

26.1 

8.14 

6.53 

8  23 

6.61 

8.43 

6.77 

8  62 

6.92 

8  82 

26.2 

8  21 

6.59 

8  30 

6.66 

8  50 

6.82 

8  69 

6.98 

8  89     1 

26.3 

8  27 

6.64 

8  37 

6.72 

8.57 

6.88 

875 

7.03 

8.96 

26.4 

8.34 

6.70 

8  44 

6.78 

8  63 

6.93 

8  82 

7.09 

9.03 

26.5 

8.41 

6.75 

8.50 

6.83 

8  70 

6.99 

8.89 

7.15 

9  10 

26.6 

8.48 

6.81 

8  57 

6.88 

8  77 

7.04 

8  96 

7.20 

9.16 

26.7 

8.55 

6.86 

8  64 

6.94 

8.84 

7.10 

9  03 

7.26 

9  23 

26.8 

8.62 

6.92 

8.71 

6.99 

8  91 

7.15 

9.10 

7.31 

9.30 

26.9 

8.68 

6.97 

8.78 

7.05 

8  98 

7.21 

9.17 

7.37 

9.37 

27.0 

8.75 

7.03 

8.85 

7.11 

9  05 

7.27 

9.23 

7.42 

9.44 

27.1 

8.82 

7.08 

8  91 

7.16 

9.11 

7.32 

9  30 

7.48 

9.51 

27.2 

8  89 

7.14 

8.98 

7.22 

9  18 

7.38 

9.37 

7.54  . 

9  58 

27.3 

8  95 

7.19 

9  05 

7.27 

9  25 

7.43 

9.44 

7.59 

9  65 

27.4 

9  02 

7.25 

9  12 

7.33 

9.32 

7.49 

9.51 

7.65 

9.71 

27.5 

9  09 

7.30 

9  19 

7.38 

9.38 

7.54 

9  58 

7.70 

9.78 

27.6 

9  16 

7.36 

9  26 

7.44 

9  45 

7.60 

9  65 

7.76 

9  85 

27.7 

9  22 

7.41 

9  32 

7.49 

9.52 

7.65 

9  72 

7.82 

9.91 

27.8 

9  29 

7.47 

9  39 

7.55 

9.59 

7.71 

9.79 

7.87 

9.98 

27  9 

9  36 

7.52 

9  46 

7.60 

9.65 

7.76 

9.86 

7.93 

10.05 

XVI] 


Table.— Continued. 


213 
6 


21°  C. 

22° 

c. 

23° 

c. 

24° 

c. 

25° 

C. 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

SCALE 
READING 

by 

by 

by 

by 

by 

by 

by 

by 

by 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

5.SA 

6.86 

5.50 

7.06 

5.66 

7.24 

5.81 

7.45 

5.97 

23.0 

5.10 

6  93 

5.66 

7.13 

5.71 

7.32 

5.87 

7.52 

6.03 

23  1 

B.46 

7.00 

5.61 

7  20 

5.77 

7  39 

5.93 

7.59 

6.08 

23.2 

5.51 

7.07 

5.67 

7  27 

5.83 

7.46 

5.98 

7  66 

6.14 

23.3 

5.57 

7.14 

5.73 

7.34 

5.89 

7.53 

6.04 

7.73 

6.20 

23.4 

5.es 

7  21 

5.78 

7.41 

5.94 

7.60 

6.10 

7.80 

6.25 

23.5 

5.69 

7.28 

5.84 

7.48 

6.00 

7  67 

6.15 

7.87 

6.31 

23.6 

5.7h 

7.35 

5.89 

7.55 

6.06 

7.74 

6.21 

7.94 

6.37 

23.7 

5.80 

7.42 

5.95 

7  62 

6.11 

7  81 

6.27 

8.00 

6.42 

23  8 

5.86 

7  49 

6.01 

7.69 

6.17 

7.88 

6.32 

8.07 

6.48 

23.9 

5.92 

7.56 

6.07 

7  76 

6.22 

7  96 

6.38 

8  14 

6.53 

24.0 

5.97 

7  63 

6.12 

7  83 

6.28 

8  02 

6.44 

8.21 

6.59 

24.1 

6  0^ 

7.70 

6.18 

7.90 

6.34 

8  09 

6.49 

8.28 

6.65 

24.2 

6.08 

7.77 

6.24 

7.97 

6.39 

8  16 

6.55 

8.35 

6.70 

24.3 

6.U 

7  84 

6.29 

8.04 

6.45 

8  23 

6.60 

8.42 

6.76 

24.4 

6.20 

7  91 

6.35 

8  10 

6.50 

8  30 

6.66 

8.48 

6.81 

24.5 

6.25 

7  98 

6.41 

8.17 

6.56 

8.37 

6.72 

8.56 

6.87 

24  6 

6.  SI 

8.05 

6.46 

8.24 

6.62 

8.44 

6.77 

8.62 

6.93 

24.7 

6.S6 

8  12 

6.52 

8.31 

6.67 

8.51 

6.83 

8  69 

6.98 

24.8 

6.42 

8.19 

6.58 

8.38 

6.73 

8.58 

6.89 

8.76 

7.04 

24.9 

6.47 

8.26 

6.63 

8.45 

6.79 

8  64 

6.94 

8.84 

7.10 

25.0 

6.5S 

8  33 

6.69 

8.52 

6.84 

8.71 

7.00 

8.91 

7.15 

25.1 

6.59 

8  40 

6.75 

8  59 

6.90 

8.78 

7.06 

8  98 

7.21 

25.2 

6.64 

8.47 

6.80 

8  66 

6.96 

8  85 

7.11 

9  05 

7.27 

25.3 

6.70 

8  54 

6.86 

8  73 

7.01 

8.92 

7.17 

9  12 

7.33 

25.4 

6.75 

8  61 

6.92 

8  80 

7.07 

8  99 

7.23 

9.19 

7.38 

25.5 

6.81 

8  68 

6.97 

8  86 

7.12 

9  06 

7.28 

9.26 

7.44 

25.6 

6.87 

8  75 

7.03 

8  93 

7.18 

9  13 

7.34 

9  33 

7.50 

25.7 

6.92 

8  82 

7.08 

9.00 

7.23 

9  20 

7.40 

9  39 

7.55 

25.8 

6.98 

8.89 

7.14 

9.07 

7.29 

9.27 

7.45 

9  46 

7.61 

25.9 

7.0S 

8  95 

7.19 

9  14 

7.35 

9.34 

7.51 

9  53 

7.67 

26.0 

7.09 

9  02 

7.25 

9  21 

7.40 

9  41 

7.56 

9.60 

7.73 

26.1 

7.14 

9.09 

7.30 

9  28 

7.46 

9.48 

7.62 

9  67 

7.78 

26.2 

7.20 

9  16 

7.36 

9  35 

7.51 

9.55 

7.68 

9  74 

7.84 

26.3 

7.25 

9  22 

7.41 

9.42 

7.57 

9  61 

7.73 

9  81 

7.90 

26.4 

7. SI 

9  29 

7.47 

9.49 

7.63 

9.68 

7.79 

9  88 

7.95 

26.5 

7.S6 

9  36 

7.52 

9.55 

7.68 

9.75 

7.85 

9  95 

8.01 

26.6 

7.42 

9  43 

7.58 

9  62 

7.74 

9.82 

7.90 

10  02 

8.07 

26.7 

7.47 

9.49 

7.63 

9  69 

7.79 

9  89 

7.96 

10  09 

8.12 

26.8 

7.5S 

9  66 

7.69 

9.76 

7.85 

9  96 

8.02 

10.16 

8.18 

26.9 

7.59 

9  63 

7.74 

9  83 

7.91 

10  03 

8.07 

10  23 

8.24 

27.0 

7.65 

9.70 

7.80 

9.90 

7.96 

10.10 

8.13 

10  30 

8.29 

27.1 

7.70 

9  76 

7.85 

9.97 

8.02 

10.17 

8.18 

10  37 

8.35 

27.2 

7.76 

9  83 

7.91 

10.03 

8.07 

10.24 

8.24 

10.44 

8.40 

27.3 

7.81 

9  90 

7.96 

10.10 

8.13 

10.31 

8.S0 

10.51 

8.46 

27.4 

7.86 

9.97 

8.02 

10.17 

8.18 

10.38 

8.S5 

10.58 

8.52 

27.5 

7.92 

10.03 

8.07 

10.24 

8.24 

10.45 

8.41 

10.65 

8.57 

27.6 

7.97 

10.10 

8.13 

10.31 

8.30 

10.51 

8.46 

10.72 

8.6S 

27.7 

8. OS 

10.17 

8.18 

10  38 

8. 85 

10.58 

8.52 

10.79 

8.69 

27.8 

8.08 

10.24 

8.24 

10.45 

8.41 

10.65 

8.58 

10.86 

8.74 

27.9 

214 


METHODS    OF   ANALYSIS 


[Chap. 


6 

Table  17.- 

-Alcohc 

17.5 

°C. 

18 

C. 

19° 

C. 

20 

C. 

21°  C. 

SCALE 
READING 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

by 

by 

by 

by 

by 

by 

by 

by 

by 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

28.0 

9.43 

7.58 

9.53 

7.66 

9.72 

7.82 

9  92 

7.98 

10  12 

28.1 

9  50 

7.64 

9  59 

7.71 

9  79 

7.87 

9.99 

8.04 

10  18 

28.2 

9  57 

7.69 

9  66 

7.77 

9  86 

7.93 

10  06 

8.09 

10  25 

28.3 

9  64 

7.75 

9  73 

7.82 

9  92 

7.98 

10  13 

8.15 

10  32 

28.4 

9.70 

7.80 

9  80 

7.88 

9  99 

8.04 

10  19 

8.20 

10  39 

28.5 

9  77 

7.86 

9  86 

7.93 

10.06 

8.09 

10  26 

8.26 

10  45 

28.6 

9  84 

7.91 

9  93 

7.99 

10.13 

8.15 

10  32 

8.31 

10.52 

28.7 

9  91 

7.97 

10  00 

8.04 

10  19 

8.20 

10  39 

8.36 

10.59 

28.8 

9  97 

8.02 

10  07 

8.10 

10.26 

8.26 

10  46 

8.42 

10.66 

28.9 

10.04 

8.08 

10  13 

8.15 

10  32 

8.31 

10  52 

8.47 

10.73 

29.0 

10.10 

8.13 

10  19 

8.20 

10.39 

8.36 

10  59 

8.53 

10  79 

29.1 

10.17 

8.18 

10  26 

8.26 

10  46 

8.42 

10  66 

8.58 

10  86 

29.2 

10.24 

8.U 

10  33 

8.31 

10  52 

8.47 

10  73 

8.64 

10  93 

29.3 

10.30 

8.29 

10  40 

8.37 

10  59 

8.53 

10  79 

8  69 

11.00 

29.4 

10.36 

8.34 

10  46 

8.42 

10.66 

8.58 

10.86 

8.74 

11.06 

29.5 

10  43 

8.40 

10  52 

8.47 

10.73 

8.64 

10  93 

8.80 

11  13 

29.6 

10  50 

8.45 

10  59 

8.53 

10.79 

8.69 

10  99 

8.85 

11  20 

29.7 

10  56 

8.50 

10  66 

8.58 

10.86 

8.74 

11.06 

8.91 

11.27 

29.8 

10  63 

8.56 

10  72 

8.63 

10  93 

8.80 

11.12 

8.96 

11  33 

29.9 

10  69 

8.61 

10  79 

8.69 

10.99 

8.85 

11.19 

9.02 

11.39 

30.0 

10.76 

8.66 

10  86 

8.74 

11.06 

8.91 

11  26 

9.07 

11.46 

30.1 

10  83 

8.72 

10  93 

8.80 

11.12 

8.96 

11  32 

9.12 

11.52 

30.2 

10  89 

8.77 

10  99 

8.85 

11.18 

9.02 

11  38 

9.18 

11  59 

30.3 

10  95 

8.82 

11  05 

8.90 

11  25 

9.07 

11  45 

9.23 

11.66 

30.4 

11  02 

8.88 

11  12 

8.96 

11  31 

9.12 

11  51 

9.28 

11.72 

30.5 

11  08 

8.93 

11  18 

9.01 

11  38 

9.18 

11.58 

9.34 

11  79 

30.6 

11  15 

8.98 

11  25 

9.06 

11.44 

9.23 

11  64 

9.39 

11  85 

30.7 

11  21 

9.04 

11  31 

9.12 

11  51 

9.28 

11  71 

9.44 

11  92 

30.8 

11  28 

9.09 

11  38 

9.17 

11.58 

9.34 

11  78 

9.50 

11  99 

30.9 

11  34 

9.14 

11  44 

9.22 

11  64 

9.39 

11  84 

9.55 

12  05 

31.0 

11  41 

9.19 

11  51 

9.28 

11  71 

9.4^ 

11  91 

9.60 

12  12 

31.1 

11  47 

9.25 

11  57 

9.33 

11.77 

9.49 

11  97 

9.66 

12  18 

31.2 

11.54 

9.30 

11  64 

9.38 

11  84 

9.55 

12  04 

9.71 

12  25 

31.3 

11  60 

9.35 

11.70 

9.43 

11  90 

9.60 

12.11 

9.76 

12  32 

31.4 

11.66 

9.40 

11  77 

9.49 

11.97 

9.65 

12  17 

9.82 

12.38 

31.5 

11  73 

9.46 

11  83 

9.54 

12  03 

9.71 

12.24 

9.87 

12  45 

31.6 

11.79 

9.51 

11  90 

9.59 

12  10 

9.76 

12  30 

9.92 

12  51 

31.7 

11  86 

9.56 

11.96 

9.65 

12.16 

9.81 

12  37 

9.98 

12.58 

31.8 

11.92 

9.62 

12.03 

9.70 

12  23 

9.87 

12.43 

10.03 

12  64 

31.9 

11.99 

9.67 

12.09 

9.75 

12.29 

9.92 

12  50 

10.09 

12.71 

32.0 

12  05 

9.72 

12.15 

9. SO 

12.36 

9.97 

12.57 

10.14 

12.78 

32.1 

12.12 

9.77 

12.21 

9.86 

12.42 

10.0.; 

12  63 

10.19 

12.84 

32.2 

12.18 

9.83 

12  28 

9.91 

12.49 

10.08 

12.70 

10.25 

12.91 

32.3 

12.24 

9.88 

12  34 

9.96 

12.55 

10.13 

12  76 

10.30 

12  97 

32.4 

12.31 

9.93 

12.40 

10.02 

12.62 

10.19 

12.83 

10.35 

13.04 

32.5 

12  37 

9.98 

12  47 

10.07 

12.68 

10.24 

12.89 

10.41 

13.10 

32.6 

12.43 

10.04 

12.54 

10.12 

12.75 

10.29 

12.96 

10.46 

13.17 

32.7 

12.50 

10.09 

12  60 

10.17 

12.81 

10.34 

13  03 

10.52 

13.24 

32.8 

12.56 

10.14 

12.67 

10.23 

12.88 

10.40 

.13.09 

10.57 

13.30 

32.9 

12  62 

10.19 

12.73 

10.28 

12.  S4 

10.45 

13.15 

10.62 

13  37 

XVI] 


215 


Table. — Continued. 


21°  C. 

22 

C. 

23° 

c. 

24° 

C. 

25°  C. 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

SCALE 
READING 

by 

by 

by 

by 

by 

by 

by 

by 

by 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

8.H 

10  31 

8.30 

10  51 

8.46 

10  72 

8.63 

10  93        8.80 

28.0 

8.19 

10  38 

8.35 

10  58 

8.52 

10  79 

8.69 

10  99        8.86 

28.1 

8.25 

10  45 

8.41 

10  65 

8.58 

10  86 

8.74 

11.06        8.91 

28.2 

8.S0 

10  52 

8.46 

10.72 

8.63 

10  93 

8.80 

1113        8.97 

2S.3 

8.S6 

10  59 

8.52 

10  79 

8.69 

11  00 

8.86 

11.20        9.02 

28.4 

8.41 

10  66 

8.58 

10  86 

8.74 

11  06 

8.91 

1127         9.08 

28.5 

8.47 

10  72 

8.63 

10  93 

8.80 

11  13 

8.97 

1133        9.13 

28.6 

8.52 

10  79 

8.69 

11  00 

8.86 

11.20 

9.02 

11.40         9.19 

28.7 

8.58 

10.86 

8.74 

11.06 

8.91 

11.27 

9.08 

11.47        9.24 

28.8 

8.64 

10  93 

8.80 

11.13 

8.97 

11  33 

9.13 

1154        9.30 

28.9 

8.69 

11  00 

8.86 

11  20 

9.02 

11  40 

9.19 

11.61        9.36 

29.0 

8.75 

11  06 

8.91 

11  27 

9.08 

11  47 

9.24 

1168        9.41 

29.1 

8.80 

11.13 

8.97 

11.33 

9.13 

11  54 

9.30 

11.75        9.47 

29.2 

8.86 

11  20 

9.02 

11.40 

9.19 

11.60 

9.35 

11.81        9.62 

29.3 

8.91 

11  27 

9.08 

11.47 

9.24 

11.67 

9.41 

11.88        9.58 

29.4 

8.97 

11  33 

9.13 

11  54 

9.30 

11  74 

9.46 

11.94        9.63 

29.5 

9.02 

11.39 

9.18 

11  60 

9.35 

11.81 

9.52 

12.01        9.69 

29.6 

9.08 

11  46 

9.24 

11.67 

9.41 

11  87 

9.67 

12.08        9.75 

29.7 

9.13 

11  53 

9.29 

11.74 

9.46 

11  94 

9.63 

12.15        9.80 

29.8 

9.18 

11  60 

9.35 

11.81 

9.52 

12  01 

9.69 

12.22        9.86 

29.9 

9.24 

11  66 

9.40 

11.87 

9.67 

12  08 

9.74 

12.29        9.91 

30.0 

9.29 

11  73 

9.46 

11  93 

9.63 

12  14 

9.80 

12.36        9.97 

30.1 

9.S4 

11  79 

9.51 

12  00 

9.68 

12  21 

9.85 

12  42      10.02 

30.2 

9.40 

11  86 

9.57 

12  07 

9.74 

12  28 

9.91 

12  49       10.08 

30.3 

9.45 

11  93 

9.62 

12  13 

9.79 

12  34 

9.96 

12.56       10.13 

30.4 

9.50 

11  99 

9.67 

12  20 

9.  So 

12  41 

10.02 

12.63       10.19 

30.5 

9.56 

12  06 

9.73 

12  27 

9.90 

12  48 

10.07 

12.70      10.24 

30.6 

9.61 

12  13 

9.78 

12  34 

9.96 

12  55 

10.13 

12.77      10.30 

30.7 

9.67 

12  19 

9.84 

12  40 

10.01 

12  61 

10.18 

12  84      10.36 

30.8 

9.72 

12  26 

9.89 

12  47 

10.07 

12  68 

10.24 

12,90      10.41 

30.9 

9.77 

12  32 

9.95 

12  54 

10.12 

12.76 

10.29 

12.97       10.47 

31.0 

9.83 

12  39 

10.00 

12  60 

10.17 

12  82 

10.35 

13.04       10.52 

31.1 

9.88 

12  46 

10.05 

12  67 

10.23 

12  89 

10.40 

13.11       10.58 

31.2 

9.94 

12  52 

10.11 

12  74 

10.28 

12  95 

10.46 

13.17      10.63 

31.3 

9.99 

12  59 

10.16 

12  81 

10.34 

13  02 

10.51 

13.24      10.69 

31.4 

10.04 

12  66 

10.22 

12  87 

10.39 

13  09 

10.67 

13.31       10.74 

31.5 

10.10 

12  72 

10.27 

12  94 

10.45 

13  15 

10.62 

13  37      10.80 

31.6 

10.15 

12  79 

10.32 

13  01 

10.50 

13  22 

10.68 

13.44       10.86 

31.7 

10.21 

12  85 

10.38 

13  07 

10.55 

13.29 

10.73 

13.51      10.91 

31.8 

10.26 

12  92 

10.43 

13.14 

10.61 

13.35 

10.78 

13.57      10.97 

31.9 

10.31 

12  99 

10.49 

13  20 

10.66 

13  42 

10.84 

13.64      11.02 

32.0 

10.37 

13  05 

10.54 

13  27 

10.72 

13.49 

10.90 

13.71       11.08 

32.1 

10.42 

13  12 

10.59 

13  34 

10.77 

13  55 

10.95 

13.77      11.13 

32.2 

10.48 

13  18 

10.65 

13  40 

10.83 

13.62 

11.01 

13.84      11.19 

32.3 

10.53 

13  25 

10.70 

13.47 

10.88 

13.69 

11.06 

13.91      11.24 

32.4 

10.58 

13  32 

10.76 

13  53 

10.94 

13.75 

11.11 

13  97      11.50 

32.5 

10.64 

13  38 

10.81 

13.60 

10.99 

13  82 

11.17 

14.04      11. S5 

32.6 

10.69 

13  45 

10.87 

13.66 

11.04 

13  89 

11.22 

14.11       11.41 

32.7 

10.75 

13.51 

10.92 

13.73 

11 .10 

13  95 

11.28 

14.17      11.46 

32.8 

10.  SO 

13  58 

10.97 

13  80 

11.15 

14.02 

11.33 

14  24       11.52 

32.9 

216 
6 


METHODS    OF    ANALYSIS 


[Chap. 


Table  17— Alcohc 


17.5 

°C. 

18 

C. 

19 

C. 

20 

c. 

21°  C. 

SCALE 
READING 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

by 

by 

by 

by 

by 

by 

by 

by 

by 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

33.0 

12  69 

10.24 

12.79 

10.33 

13.01 

10.50 

13.22 

10.68 

13.43 

33.1 

12.76 

10.  SO 

12  86 

10.38 

13.07 

10.56 

13  28 

10.73 

13  50 

33.2 

12  82 

10.35 

12.92 

10.43 

13.13 

10.61 

13  35 

10.79 

13  56 

33.3 

12.88 

10.40 

12.99 

10.49 

13.20 

10.66 

13.41 

10.84 

13.63 

33.4 

12.95 

10.45 

13.05 

10.54 

13.26 

10.71 

13.48 

10.89 

13.69 

33.5 

13.01 

10.50 

13.11 

10.59 

13  32 

10.77 

13.54 

10.95 

13.76 

33.6 

13.08 

10.56 

13  18 

10.64. 

13  39 

10.82 

13.61 

11.00 

13.82 

33.7 

13.14 

10.61 

13.24 

10.70 

13.45 

10.87 

13.67 

11.05 

13  89 

33.8 

13  20 

10.66 

13  30 

10.75 

13.52 

10.93 

13.74 

11.10 

13.95 

33.9 

13.26 

10.71 

13.37 

10.80 

13.58 

10.98 

13.80 

11.16 

14.02 

34.0 

13  33 

10.77 

13  43 

10.85 

13  64 

11.03 

13.86 

11.21 

14.08 

34.1 

13.39 

10.82 

13.49 

10.91 

13.71 

11.08 

13.93 

11.26 

14  15 

34.2 

13.45 

10.87 

13.56 

10.96 

13.77 

11.13 

13  99 

11.31 

14.21 

34.3 

13.52 

10.92 

13.62 

11.01 

13.83 

11.19 

14.06 

11.36 

14.27 

34.4 

13.58 

10.97 

13.68 

11.06 

13.90 

11.24 

14.12 

11.41 

14.34 

34.5 

13  64 

11.03 

13  75 

11.11 

13.96 

11.29 

14.18 

11.47 

14.40 

34.6 

13.70 

11.08 

13  81 

11.16 

14.02 

11.34 

14.25 

11.52 

14.47 

34.7 

13.77 

11.13 

13.87 

11.22 

14.08 

11.39 

14.31 

11.57 

14  53 

34.8 

13  83 

11.18 

13  94 

11.27 

14.14 

11.44 

14.37 

11.62 

14.59 

34.9 

13.89 

11.23 

14.00 

11.32 

14.20 

11.49 

14.43 

11.67 

14.66 

35.0 

13.96 

11.28 

14.06 

11.37 

14.27 

11.55 

14.50 

11.73 

14.72 

35.1 

14.02 

11.33 

14.13 

11.42 

14  33 

11.60 

14.56 

11.78 

14  78 

35.2 

14  08 

11.38 

14.19 

11.47 

14.39 

11.65 

14.62 

11.83 

14  85 

35.3 

14.14 

11.44 

14.25 

11.52 

14.46 

11.70 

14.69 

11.88 

14  91 

35.4 

14  21 

11.49 

14.31 

11.57 

14  52 

11.75 

14.75 

11.93 

14.97 

35.5 

14.27 

11.54 

14.38 

11.63 

14  59 

11.81 

14  81 

11.99 

15  04 

35.6 

14  33 

11.59 

14.44 

11.68 

14  65 

11.86 

14  87 

12.04 

15  10 

35.7 

14.39 

11.64 

14.50 

11.73 

14.71 

11.91 

14.94 

12.09 

15  16 

35.8 

14.46 

11.69 

14  56 

11.78 

14.78 

11.96 

15.00 

12.14 

15  23 

35.9 

14.52 

11.74 

14.63 

11.83 

14.84 

12.01 

15.06 

12.19 

15.29 

36.0 

14.58 

11.79 

14  69 

11.88 

14.90 

12.06 

15.13 

12.24 

15  35 

36.1 

14.64 

11.85 

14.75 

11.94 

14.97 

12.11 

15.19 

12.30 

15  42 

36.2 

14.71 

11.90 

14.81 

11.99 

15  03 

12.16 

15  25 

12.35 

15  48 

36.3 

14.77 

11.95 

14  88 

12.04 

15  09 

12.22 

15.32 

12.40 

15  54 

36.4 

14.83 

12.00 

14  94 

12.09 

15.16 

12.27 

15.38 

12.45 

15.61 

36.5 

14.89 

12.05 

15  00 

12.14 

15  22 

12.32 

15.44 

12.50 

15  67 

36.6 

14.96 

12.10 

15.06 

12.19 

15  28 

12.37 

15  51 

12.56 

15  73 

36.7 

15.02 

12.15 

15.13 

12.24 

15.35 

12.42 

15.57 

12.61 

15  80 

36.8 

15.08 

12.20 

15  19 

12.29 

15.41 

12.47 

15  63 

12.66 

15  86 

36.9 

15.14 

12.25 

15.25 

12.34 

15.47 

12.53 

15.70 

12.71 

15  92 

37.0 

15  20 

12.30 

15.31 

12.40 

15.53 

12.58 

15.76 

12.77 

15  99 

37.1 

15  27 

12.36 

15  38 

12.45 

15  60 

12.63 

15.82 

12.82 

16  05 

37.2 

15  33 

12.41 

15.44 

12.50 

15.66 

12.68 

15  89 

12.87 

16.11 

37.3 

15.39 

12.46 

15.50 

12.55 

15  72 

12.73 

15.95 

12.92 

16.18 

37.4 

15.45 

12.51 

15.56 

12.60 

15.79 

12.78 

16  01 

12.97 

16.24 

37.5 

15.51 

12.56 

15.63 

12.65 

15  85 

12.84 

16.08 

13.03 

16  30 

37.6 

15.57 

12.61 

15.69 

12.70 

15  91 

12.89 

16.14 

13.08 

16.37 

37.7 

15.64 

12.66 

15.75 

12.75 

15.97 

12.94 

16.20 

13.13 

16.43 

37.8 

15.70 

12.71 

15.81 

12.81 

16.04 

12.99 

16.26 

13.18 

16.49 

37.9 

15.76 

12.76 

15  88 

12.86 

16  10 

13.04 

16  33 

13.23 

16  56 

XVI] 


Table. — Continued. 


217 
6 


21°  C. 

22° 

C. 

23° 

c. 

24 

C. 

25 

'C. 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

SCALE 
BEADING 

by 

by 

by 

by 

by 

by 

by 

by 

by 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

10.85 

13.64 

11.03 

13.86 

11.21 

14  09 

11.39 

14  31 

11.57 

33.0 

10.91 

13.71 

11.08 

13.93 

11.26 

14.15 

11.44 

14.38 

11.63 

33.1 

10.96 

13  78 

11.13 

13.99 

11.81 

14.22 

11.49 

14.44 

11.68 

33.2 

11.02 

13  84 

11.19 

14.06 

11.37 

14  28 

11.55 

14  51 

11.74 

33.3 

11.07 

13  91 

11.24 

14.13 

11.42 

14.35 

11.60 

14.58 

11.79 

33.4 

11.12 

13.97 

11.29 

14.19 

11.48 

14.42 

11.66 

14.64 

11.85 

33.5 

11.17 

14  04 

11.35 

14.26 

11.53 

14  48 

11.71 

14.71 

U.90 

33.6 

11.23 

14.11 

11.40 

14  32 

11.58 

14.65 

11.77 

14  78 

11.96 

33.7 

11.28 

14.17 

11.45 

14  39 

11.64 

14.62 

11.82 

14  86 

12.01 

33.8 

11.33 

14.24 

11.51 

14.45 

11.69 

14.68 

11.88 

14  91 

12.07 

33.9 

11.38 

14  30 

11.56 

14.62 

11.75 

14.75 

11.93 

14.98 

12.12 

34.0 

11. U 

14.37 

11.61 

14.59 

11.80 

14.81 

11.98 

16  06 

12.18 

34.1 

11.49 

14.43 

11.67 

14  65 

11.85 

14.88 

12.04 

15.11 

12.23 

34.2 

11.54 

14.50 

11.72 

14.72 

11.91 

14.95 

12.09 

15.18 

12.29 

34.3 

11.59 

14.57 

11.78 

14.78 

11.96 

16.01 

12.15 

15.26 

12.34 

34.4 

11.65 

14.63 

11.83 

14.85 

12.02 

15.08 

12.20 

15  31 

12.40 

34.5 

11.70 

14.70 

11.88 

14.91 

12.07 

15  14 

12.26 

16.38 

12.45 

34.6 

11.75 

14.76 

11.94 

14.98 

12.12 

15  21 

12.31 

16  45 

12.51 

34.7 

11.81 

14.83 

11.99 

15  06 

12.18 

15  28 

12.36 

16  51 

12.56 

34.8 

11.86 

14.89 

12.04 

15.11 

12.23 

16.34 

12.42 

15  68 

12.62 

34.9 

11.91 

14.96 

12.10 

15  18 

12.28 

15.41 

12.47 

15.66 

12.67 

35.0 

11.96 

15.03 

12.15 

15.24 

12.34 

15.47 

12.53 

15  71 

12.78 

35.1 

12.02 

15.09 

12.20 

15.31 

12.39 

15  54 

12.58 

15  78 

12.78 

35.2 

12.07 

15.15 

12.25 

15  37 

12. U 

15  61 

12.64 

16  86 

12.84 

35.3 

12.12 

15  22 

12.31 

15.44 

12.50 

16  67 

12.69 

15  91 

12.89 

35.4 

12.17 

15  28 

12.36 

15  50 

12.55 

15.74 

12.75 

16  98 

12.95 

35.5 

12.23 

15.34 

12.41 

15.66 

12.60 

15.80 

12.80 

16  05 

1.1.00 

35.6 

12.28 

15.41 

12.47 

15  63 

12.66 

15.87 

12.85 

16  11 

13.05 

35.7 

12.33 

15.47 

12.52 

15  69 

12.71 

15  93 

12.91 

16  18 

13.11 

35.8 

12.38 

15.53 

12.57 

15.76 

12.76 

16  00 

12.96 

16  24 

13.16 

35.9 

12.43 

15.59 

12.62 

15  82 

12.82 

16  06 

13.02 

16  31 

13.21 

36.0 

12.49 

15  66 

12.68 

15.89 

12.87 

16.13 

13.07 

16  37 

13.27 

36.1 

12.54 

15  72 

12.73 

15  96 

12.92 

16  19 

13.12 

16.44 

13.32 

36.2 

12.59 

15  78 

12.78 

16.02 

12.98 

.16.26 

13.18 

16  50 

13.37 

36.3 

12.64 

15.85 

12.84 

16  08 

13.08 

16  32 

13.23 

16.56 

13.43 

36.4 

12.70 

15  91 

12.89 

16.15 

13.08 

16  39 

13.28 

16  63 

18.48 

36.5 

12.75 

15.97 

12.94 

16.21 

18.14 

16  45 

13.34 

16  69 

13.5.3 

36.6 

12.80 

16.04 

12.99 

16.28 

13.19 

16.52 

13.39 

16.76 

13.59 

36.7 

12.85 

16.10 

13.05 

16  34 

13.24 

16  58 

18. U 

16  82 

13.64 

36.8 

12.91 

16.16 

13.10 

16.40 

13.29 

16.65 

13.49 

16  89 

13.70 

36.9 

12.96 

16  23 

13.15 

16.47 

13.35 

16.71 

13.55 

16  95 

13.75 

37.0 

18.01 

16  29 

13.20 

16.53 

18.40 

16.77 

13.60 

17.02 

18.80 

37.1 

IS. 06 

16  35 

13.26 

16.60 

13.45 

16  84 

13.65 

17.08 

13.86 

37.2 

13.11 

16.42 

13.31 

16.66 

13.50 

16.90 

13.71 

17.15 

13.91 

37.3 

13.16 

16.48 

13.36 

16.72 

18.56 

16.97 

13.76 

17.21 

13.96 

37.4 

IS. 21 

16  54 

13.41 

16.79 

13.61 

17  03 

13.81 

17.27 

14.02 

37.5 

1S.27 

16.61 

13.46 

16.85 

18.66 

17.09 

13.87 

17.34 

14.07 

37.6 

1S.S2 

16  67 

13.52 

16.92 

18.72 

17.16 

18.92 

17.40 

14.12 

37.7 

13.37 

16.73 

13.57 

16.98 

18.77 

17.22 

13.97 

17.46 

14.17 

37.8 

13.42 

16.80 

13.62 

17.04 

13.82 

17.28 

14.03 

17.53 

14.2s 

37.9 

218 


METHODS    OF   ANALYSIS 


[Chap. 


6 

Table  17.— 

Alcohc 

17.5 

'C. 

18° 

C. 

19° 

C. 

20° 

C. 

21°C. 

SCALE 
READING 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cen 

by 

by 

by 

by 

by 

by 

by 

by 

by 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

38.0 

15  82 

12.81 

15  94 

12.91 

16  16 

13.09 

16  39 

13.28 

16  62 

38.1 

15  88 

12.86 

16  00 

12-96 

16  22 

13.14 

16  46 

13.33 

16  68 

38.2 

15  94 

12.91 

16  06 

13.01 

16  29 

13.19 

16.51 

13.38 

16  75 

38.3 

16.01 

12.96 

16  12 

13.06 

16  35 

13.25 

16  57 

13.44 

16.81 

38.4 

16.07 

IS. 02 

16  18 

13.11 

16  41 

13.30 

16.64 

13.49 

16.87 

38.5 

16  13 

13.07 

16  25 

13.16 

16.47 

13.35 

16.70 

13.54 

16  94 

38.6 

16  19 

IS. 12 

16  31 

13.21 

16  53 

13.40 

16  76 

13.59 

17.00 

38.7 

16  25 

13.17 

16  37 

13.26 

16  60 

13. 4S 

16  83 

13.64 

17  06 

38.8 

16  31 

13.22 

16.43 

13.31 

16.66 

13.50 

16  89 

13.69 

17  13 

38.9 

16  37 

13.27 

16  49 

13.37 

16.72 

13.55 

16  95 

13.74 

17.19 

39.0 

16  44 

13.32 

16  55 

13.42 

16  78 

13.61 

17.01 

13.79 

17  25 

39.1 

16  50 

13.37 

16  61 

13.47 

16  84 

13.66 

17.07 

IS. 85 

17  31 

39.2 

16  56 

13.42 

16  67 

13.52 

16  91 

13.71 

17.14 

13.90 

17.38 

39.3 

16.62 

13.47 

16.74 

13.57 

16.97 

13.76 

17.20 

13.95 

17.44 

39.4 

16.68 

IS. 52 

16  80 

13.62 

17.03 

IS. 81 

17.26 

14.00 

17.60 

39.5 

16  74 

13.57 

16  86 

13.67 

17.09 

13.86 

17  32 

14-05 

17  56 

39.6 

16  80 

13.62 

16  92 

13.72 

17.15 

13.91 

17  39 

14.10 

17.63 

39.7 

16  87 

13.68 

16  98 

13.77 

17.21 

13.96 

17.45 

14-15 

17  69 

39.8 

16  93 

13.73 

17.04 

13.82 

17.28 

14-02 

17.51 

14-21 

17.75 

39.9 

16  99 

13.78 

17  10 

13.87 

17.34 

14-07 

17.57 

14-26 

17.81 

40.0 

17.05 

13.83 

17  16 

13.92 

17.40 

14.12 

17.63 

14.31 

17.88 

40.1 

17  11 

13.88 

17  23 

13.98 

17.46 

14-17 

17.70 

14-36 

17  94 

40.2 

17  17 

13.93 

17  29 

14-03 

17  52 

14-22 

17.76 

14-41 

18  00 

40.3 

17  23 

13.98 

17  35 

14-08 

17  58 

14-27 

17  82 

14-46 

18  06 

40.4 

17  29 

14.03 

17  41 

14-13 

17.64 

14-32 

17  88 

14-51 

18  12 

40.5 

17  35 

14-08 

17.47 

14-18 

17  71 

14-37 

17  94 

14-56 

18  19 

40.6 

17.41 

14.13 

17  53 

14-23 

17.77 

14-42 

18  01 

14-62 

18  25 

40.7 

17.48 

14-18 

17  59 

14-28 

17  83 

14-47 

18  07 

14-67 

18  31 

40.8 

17.54 

14-23 

17  65 

14-33 

17  89 

14-52 

18  13 

14-72 

18  37 

40.9 

17.60 

14-28 

17  71 

14-38 

17  95 

14-57 

18  19 

14-77 

18.43 

41.0 

17.66 

14-33 

17  77 

14-43 

18  01 

14-62 

18  25 

14-82 

18  49 

41.1 

17  72 

14-38 

17  84 

14-48 

18.07 

14-68 

18  31 

14.87 

18  56 

41.2 

17.78 

14-43 

17  90 

14-53 

18  13 

14-73 

18  37 

14-92 

18  62 

41.3 

17.84 

14-48 

17  96 

14-58 

18  20 

14-78 

18  44 

14.97 

18  68 

41.4 

17.90 

14.53 

18  03 

14-63 

18  26 

14-83 

18  50 

15.03 

18.74 

41.5 

17.96 

14-58 

18  08 

14-68 

18  32 

14-88 

18  56 

15.08 

18  80 

41.6 

18  02 

14-63 

18  14 

14-73 

18  38 

14-93 

18  62 

15.13 

18  86 

41.7 

18  08 

14-68 

18  20 

14-78 

18.44 

14-98 

18  68 

15.18 

18  93 

41.8 

18  14 

14-73 

18  26 

14-83 

18  50 

15.03 

18  74 

15.23 

18  99 

41.9 

18  20 

14.78 

18  32 

14-88 

18.56 

15.08 

18  81 

15.28 

19.05 

42.0 

18  27 

14-83 

18  38 

14-93 

18  62 

15.13 

18  87 

15.38 

19  11 

42.1 

18  33 

14-88 

18  44 

14-98 

18  68 

15.18 

18  93 

15.38 

19  17 

42.2 

18  39 

14-93 

18  50 

15.03 

18  74 

15.23 

18  99 

15.43 

19  23 

42.3 

18.45 

14-98 

18  56 

15.08 

18  80 

15.28 

19.05 

15.48 

19  29 

42.4 

18.51 

15.03 

18.62 

15.13 

18  87 

15.33 

19.11 

15.53 

19  36 

42.5 

18  57 

15.08 

18  68 

15.18 

18  93 

15.38 

19.17 

15.58 

19  42 

42.6 

18  63 

15.13 

18  75 

15.23 

18  99 

15.43 

19  23 

15.63 

19  48 

42.7 

18  69 

15.18 

18  81 

15.28 

19  05 

15.48 

19  29 

15.69 

19  54 

42.8 

18.75 

15.23 

18  87 

15.33 

19.11 

15.53 

19  36 

15.74 

19  60 

42.9 

18.81 

15.28 

18.93 

15.38 

19.17 

15.58 

19.42 

15.79 

19.66 

XVI] 

WINES 

219 

Table- 

-Continued. 

6 

21  "C. 

2: 

^C. 

23° 

c. 

24 

°C. 

25 

c. 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  o«nt 

BCALE 
BEADINO 

by 

by 

by 

by 

by 

by 

by 

by 

by 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

75. 47 

16  86 

13.67 

17.11 

13.87 

17.36 

14. 08 

17  69 

14-28 

38.0 

IS.  53 

16  92 

13.72 

17.17 

13.93 

17.41 

14.13 

17.66 

14.33 

38.1 

IS.  58 

16  99 

13.78 

17.23 

13.98 

17.47 

14. 18 

17.72 

14.38 

38.2 

.  IS. 63 

17.05 

13.83 

17  30 

14.03 

17.54 

14.23 

17.78 

14.4s 

38.3 

1  1S.G8 

17.11 

13.88 

17.36 

I4.O8 

17.60 

14.29 

17.86 

14.49 

38.4 

IS. 73 

17.18 

13.93 

17,42 

14.14 

17.66 

14.34 

17.91 

14-54 

38.5 

1  IS. 79 

17  24 

13.98 

17.48 

14.19 

17.73 

14.39 

17  97 

14.59 

38.6 

i  1S.8A 

17  30 

14.04 

17.55 

14.24 

17  79 

14.44 

18.04 

14.64 

38.7 

1  1S.89 

17  36 

14.09 

17  61 

14.29 

17.86 

14.49 

18.10 

14.70 

38.8 

1  lS.9i 

17.43 

14.14 

17.67 

14.34 

17.92 

14.66 

18.16 

14.75 

38.9 

\  IS. 99 

17  49 

14.19 

17  74 

14.40 

17.98 

14.60 

18  23 

14.80 

39.0 

1  14.05 

17  55 

14.24 

17.80 

14-45 

18  04 

14.65 

18.29 

14.85 

39.1 

'  M.JO 

17  62 

14.30 

17.86 

14-50 

18  11 

14.70 

18.36 

14.91 

39.2 

J4./5 

17  68 

14.35 

17.92 

14.55 

18.17 

14.76 

18.42 

14.96 

39.3 

'  U.20 

17.74 

14-40 

17.99 

14. 60 

18  23 

14.81 

18.48 

15.01 

39.4 

1J,.25 

17  81 

14.45 

18  06 

14.66 

18  30 

14.86 

18  64 

15.06 

39.5 

14. SO 

17  87 

14.50 

18  11 

14.71 

18  36 

14.91 

18  61 

15.12 

39.6 

, 14.S6 

17  93 

14.66 

18.18 

14.76 

18  42 

14.96 

18.67 

15.17 

39.7 

<  14.41 

17.99 

14-61 

18.24 

14. 81 

18.48 

15.02 

18.73 

15.22 

39.8 

\  14. 46 

18.06 

14.66 

18  30 

14.87 

18.56 

15.07 

18.80 

15.27 

39.9 

\  14.51 

18  12 

14.71 

18  36 

14.92 

18  61 

15.12 

18  86 

16. S2 

40.0 

'  14.56 

18  18 

14.77 

18.43 

14.97 

18.67 

15.17 

18.92 

15.38 

40.1 

14-61 

18  24 

14.82 

18.49 

15.02 

18.74 

15.22 

18  99 

15.43 

40.2 

14.67 

18  30 

14.87 

18  55 

15.07 

18  80 

15.27 

19  05 

15.48 

40.3 

U.7S 

18  37 

14.92 

18  61 

15.12 

18.86 

15.33 

19.11 

15.53 

40.4 

14.77 

18  43 

14.97 

18  68 

15.17 

18  92 

15.38 

19.18 

15.59 

40.5 

14-82 

18  49 

15.03 

18.74 

15.23 

18  99 

15.43 

19  24 

15.64 

40.6 

14.87 

18  55 

15.08 

18  80 

15.28 

19  06 

15.48 

19  30 

15.69 

40.7 

14.92 

18  61 

15.13 

18.86 

15.33 

19.11 

15.53 

19  37 

15.74 

40.8 

14.97 

18  68 

15.18 

18  93 

15.38 

19.18 

16.59 

19.43 

15.80 

40.9 

15.03 

18  74 

15.2S 

18.99 

15.4s 

19  24 

15.64 

19.49 

15.85 

41.0 

15.08 

18  80 

15.28 

19  06 

15.48 

19  30 

15.69 

19  56 

15.90 

41.1 

16.13 

18  86 

15.83 

19.11 

15.53 

19  36 

15.74 

19  62 

15.95 

41.2 

16.18 

18  93 

15.38 

19  17 

15.58 

19  43 

15.79 

19  68 

16.01 

41.3 

16.23 

18  99 

15.4s 

19  24 

15.64 

19.49 

15.84 

19  75 

16.06 

41.4 

.16.28 

19  05 

15.48 

19  30 

15.69 

19  55 

15.90 

19  81 

16.11 

41.5 

16.33 

19  11 

15.53 

19  36 

15.74 

19  61 

15.95 

19  87 

16.16 

41.6 

16.38 

19  17 

15.58 

19  42 

15.79 

19.68 

16.00 

19.94 

16.21 

41.7 

15.43 

19  23 

15.63 

19.48 

15.84 

19.74 

16.05 

20.00 

16.27 

41.8 

15.48 

19  29 

15.69 

19.66 

16.89 

19.80 

16.10 

20.06 

16.32 

41.9 

15.53 

19  36 

15.74 

19  61 

15.94 

19  86 

16.16 

20  13 

16.37 

42.0 

16.58 

19  42 

15.79 

19  67 

15.99 

19  93 

16.81 

20  19 

16. 42 

42.1 

16.63 

19  48 

15.84 

19.73 

16.05 

19  99 

16.26 

20  25 

16.48 

42.2 

16.69 

19  54 

15.89 

19.80 

16.10 

20.05 

16.31 

20  31 

16.53 

42.3 

15.74 

19  60 

15.94 

19.86 

16.16 

20  11 

16. S6 

20.38 

16.58 

42.4 

16.79 

19  66 

15.99 

19  92 

16.20 

20.18 

16. 41 

20  44 

16.63 

42.5 

J  6. 84 

19.72 

16.04 

19  98 

16.25 

20  24 

16.47 

20  50 

16.79 

42.6 

15.89 

19.79 

16.09 

20  04 

16.30 

20  30 

16.52 

20.57 

16.74 

42.7 

115.94 

19  85 

16.14 

20.10 

16.35 

20  36 

16.57 

20.63 

16.79 

42.8 

16.99 

19.91 

16.19 

20.17 

16. 41 

20.43 

16.62 

20.69 

16.84 

42.9 

220 


METHODS    OF   ANALYSIS 


6 

Table  17.— 

-Algo 

17.5 

C. 

18° 

C. 

19° 

C. 

20° 

C. 

21°  ( 

SCALE 
READING 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Perc 

by 

by 

by 

by 

by 

by 

by 

by 

by 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

volu 

43.0 

18.87 

15. S3 

18  99 

15.43 

19  23 

15.63 

19  48 

15.84 

19  7 

43.1 

18  93 

15.S8 

19  05 

15.48 

19  29 

15.68 

19,54 

15.89 

19  7 

43.2 

18.99 

15. 4S 

19.11 

15.53 

19  35 

15.73 

19  60 

15.94 

198 

43.3 

19  05 

16.48 

19  17 

15.58 

19.41 

15.78 

19.66 

15.99 

19  9 

43.4 

19  11 

15.53 

19  23 

15.63 

19.47 

15.83 

19.72 

16.04 

19.9 

43.5 

19  17 

15.58 

19  29 

15.68 

19  53 

15.88 

19  79 

16.09 

20  0 

43.6 

19  23 

15.63 

19  35 

15.73 

19  59 

15.93 

19  85 

16.14 

200 

43.7 

19  29 

15.68 

19.41 

15.78 

19  65 

15.98 

19.91 

16.19 

20.1 

43.8 

19  35 

15.73 

19.47 

15.83 

19.72 

16.03 

19  97 

16.24 

20  2 

43.9 

19  40 

15.78 

19  53 

15.88 

19.78 

16.08 

20.03 

16.29 

20  2 

44.0 

19.46 

15.83 

19  59 

15.93 

19  84 

16.13 

20  09 

16.34 

203 

44.1 

19.52 

15.88 

19  65 

15.98 

19.90 

16.18 

20.15 

16.39 

20  4 

44.2 

19  58 

15.93 

19  71 

16.03 

19.96 

16.23 

20.21 

16.  U 

20  4 

44.3 

19.64 

15.98 

19  77 

16.08 

20  02 

16.28 

20.27 

16.49 

20  5 

44,4 

19  70 

16.02 

19  83 

16.13 

20.08 

16.33 

20  33 

16.55 

20  5 

44.5 

19.76 

16.07 

19  89 

16.18 

20.14 

16.38 

20.39 

16.60 

20  6 

44  6 

19  82 

16.12 

19  95 

16.23 

20.20 

16.43 

20.45 

16.65 

20  7 

44.7 

19  88 

16.17 

20  01 

16.27 

20  26 

16.48 

20  52 

16.70 

20  7 

44.8 

19  94 

16.22 

20.07 

16.32 

20  32 

16.53 

20.58 

16.75 

20  8 

44.9 

20.00 

16.27 

20.12 

16.37 

20  38 

16.58 

20.64 

16.80 

20  8 

45.0 

20  06 

16.32 

20  18 

16.42 

20.44 

16.63 

20  70 

16.85 

20  9 

45.1 

20.12 

16.37 

20.24 

16.47 

20  50 

16.68 

20  76 

16.90 

21  0 

45.2 

20.18 

16.41 

20  30 

16.52 

20  56 

16.73 

20  82 

16.95 

21  0 

45.3 

20.24 

16.46 

20  36 

16.57 

20  62 

16.78 

20  88 

17.00 

21  1 

45.4 

20  29 

16.51 

20  42 

16.62 

20  68 

16.83 

20.94 

17.05 

21  1 

45.5 

20  35 

16.56 

20.48 

16.67 

20.74 

16.88 

21.00 

17.10 

21  2 

45.6 

20  41 

16.61 

20  54 

16.72 

20  80 

16.93 

21  06 

17.15 

21  3 

45.7 

20  47 

16.66 

20  60 

16.76 

20  86 

16.98 

21  12 

17.20 

21  3 

45.8 

20  53 

16.71 

20  66 

16.81 

20  92 

17.03 

21.18 

17.25 

21  4 

45.9 

20  59 

16.76 

20.72 

16.86 

20.98 

17.08 

21.24 

17.30 

21.4 

46.0 

20  65 

16.80 

20.78 

16.91 

21  04 

17.13 

21.30 

17.35 

21  5 

46.1 

20  71 

16.85 

20  83 

16.96 

21  10 

17.18 

21.36 

17.40 

21  6 

46.2 

20  76 

16.90 

20  89 

17.01 

21  16 

17.23 

21.42 

17.45 

21  6 

46.3 

20  82 

16.95 

20.95 

17.06 

21  22 

17.28 

21.48 

17.50 

21  7 

46.4 

20  88 

17.00 

21.01 

17.11 

21  28 

17.33 

21.54 

17.55 

21  7 

46.5 

20.94 

17.05 

21  07 

17.16 

21  34 

17.38 

21.60 

17.60 

21  8- 

46.6 

21.00 

17.10 

21.13 

17.21 

21.40 

17.43 

21  66 

17.65 

21  9 

46.7 

21  06 

17.15 

21.19 

17.26 

21.46 

17.48 

21.72 

17.70 

21  9 

46.8 

21.12 

17.20 

21.25 

17.31 

21  52 

17.53 

21.78 

17.75 

22  0 

46.9 

21.18 

17.25 

21-31 

17.36 

21.58 

17.58 

21.84 

17.80 

22  0 

47.0 

21.24 

17.30 

21.37 

17.41 

21.64 

17.63 

21.90 

17.85 

22  1 

47.1 

21  30 

17.35 

21.43 

17.46 

21  70 

17.68 

21  96 

17.90 

22  2. 

47.2 

21.36 

17.40 

21.49 

17.51 

21.76 

17.73 

22.02 

17.95 

22  2' 

47.3 

21.42 

17.45 

21.55 

17.56 

21.82 

17.78 

22.08 

18.01 

22  3: 

47.4 

21.48 

17.50 

21.61 

17.61 

21.88 

17.83 

22.15 

18.06 

22  31 

47.5 

21.54 

17.55 

21.67 

17.66 

21.94 

17.88 

22  21 

18.11 

22.41 

47.6 

21.60 

17.60 

21  73 

17.71 

22.00 

17.94 

22.27 

18.16 

22.5: 

47.7 

21.66 

17.65 

21.79 

17.76 

22.06 

17.99 

22  33 

18.21 

22  5i 

47.8 

21.72 

17.70 

21.85 

17.81 

22.12 

18.04 

22.39 

18.26 

22. 6< 

47.9 

21.78 

17.75 

21.91 

17.86 

22.18 

18.09 

22.45 

18.31 

22. 7( 

XVI] 


Table. — Continued. 


221 
6 


21°  C. 

22° 

C. 

23° 

c. 

24° 

c. 

25°  C. 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

SCALE 
READINO 

bv 

by 

by 

by 

by 

by 

by 

by 

by 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

16.04 

19  97 

16.24 

20  23 

16.46 

20  49 

16.67 

20.76 

16.90 

43.0 

16.09 

20  03 

16.80 

20  29 

16.51 

20  55 

16.73 

20  82 

16.95 

43.1 

16.14 

20  09 

16.35 

20  35 

16.56 

20  61 

16.78 

20  88 

17.00 

43.2 

16.19 

20  16 

16.40 

20  41 

16.61 

20  68 

16.83 

20  94 

17.05 

43.3 

16. U 

20  21 

16.45 

20.47 

16.66 

20.74 

16.88 

21  01 

17.10 

43.4 

16.29 

20  28 

16.50 

20  53 

16.71 

20  80 

16.93 

21  07 

17.16 

43.5 

16.34 

20  34 

16.55 

20  60 

16.76 

20  86 

16.98 

21  13 

17.21 

43.6 

16.40 

20  40 

16.60 

20  66 

16.82 

20  93 

17.04 

21  19 

17.26 

43.7 

16.45 

20  46 

16.65 

20  72 

16.87 

20  99 

17.09 

21.26 

17.31 

43.8 

16.50 

20  52 

16.70 

20  78 

16.92 

21  05 

17.14 

21  32 

17.36 

43.9 

16.55 

20  58 

16.76 

20  84 

16.97 

21.11 

17.19 

21  38 

17.41 

44.0 

16.60 

20  64 

16.81 

20  90 

17.02 

21  17 

17.24 

21.44 

17.47 

44.1 

16.65 

20  71 

16.86 

20  96 

17.07 

21  23 

17.29 

21  50 

17.62 

44.2 

16.70 

20.77 

16.91 

21  02 

17.12 

21  30 

17.35 

21.57 

17.67 

44.3 

16.75 

20  83 

16.96 

21  09 

17.17 

21  36 

17.40 

21  63 

17.62 

44.4 

16.80 

20  89 

17.01 

21  15 

17.22 

21  42 

17.45 

21  69 

17.67 

44.5 

16.85 

20  95 

17.06 

21  21 

17.28 

21.48 

17.50 

21.76 

17.73 

44.6 

16.90 

21  01 

17.11 

21  27 

17.33 

21  54 

17.55 

21.81 

17.78 

44.7 

16.95 

21  07 

17.16 

21  33 

17.38 

21.60 

17.60 

21  88 

17.83 

44.8 

17.01 

21  13 

17.21 

21  39 

17.43 

21  67 

17.65 

21  94 

17.88 

44.9 

17.06 

21  19 

17.26 

21  46 

17.48 

21.73 

17.71 

22  00 

17.93 

45.0 

17.11 

21  25 

17.31 

21  52 

17.53 

21  79 

17.76 

22.06 

17.98 

45.1 

17.16 

21  31 

17.36 

21  58 

17.68 

21  85 

17.81 

22  13 

18.04 

45.2 

17.  SI 

21  37 

17.41 

21.64 

17.63 

21  91 

17.86 

22  19 

18.09 

45.3 

17.26 

21  43 

17.46 

21  70 

17.68 

21  98 

17.91 

22  25 

18.14 

45.4 

17.31 

21  49 

17.51 

21.76 

17.73 

22  04 

17.96 

22  32 

18.20 

45.5 

17.36 

21  55 

17.56 

21  82 

17.79 

22  10 

18.02 

22  38 

18.25 

45.6 

17.41 

21  61 

17.61 

21.88 

17.84 

22  16 

18.07 

22  45 

18.30 

45.7 

17.46 

21  67 

17.66 

21.94 

17.89 

22  23 

18.12 

22  51 

18.36 

45.8 

17.51 

21  73 

17.71 

22  01 

17.94 

22  29 

18.17 

22  67 

18.41 

45.9 

17.56 

21  79 

17.76 

22  07 

17.99 

22  36 

18.23 

22  64 

18.47 

46.0 

17.61 

21  85 

17.81 

22  13 

18.04 

22  42 

18.28 

22  70 

18.62 

46.1 

17.66 

21  91 

17.86 

22.19 

18.09 

22  48 

18.33 

22  76 

18.57 

46.2 

17.71 

21  97 

17.91 

22  26 

18.15 

22  54 

18.39 

22  83 

18.63 

46.3 

17.76 

22  03 

17.96 

22  32 

18.20 

22.61 

18.44 

22  89 

18.68 

46.4 

17.81 

22  09 

18.01 

22.38 

18.25 

22  67 

18.49 

22.96 

18.73 

46.5 

17.86 

22  16 

18.06 

22.44 

18.30 

22  73 

18.55 

23  02 

18.79 

46.6 

17.91 

22  22 

18.11 

22  51 

18.36 

22  80 

18.60 

23  08 

18.84 

46.7 

17.96 

22  28 

18.17 

22  57 

18.41 

22  86 

18.65 

23  16 

18.90 

46.8 

18.01 

22  34 

18.22 

22  63 

18.46 

22.92 

18.70 

23  21 

18.95 

46.9 

18.06 

22.41 

18.27 

22  69 

18.51 

22  99 

18.76 

23.28 

19.00 

47.0 

18.11 

22  47 

18.32 

22.76 

18.57 

23  05 

18.81 

23  34 

19.06 

47.1 

18.16 

22  53 

18.38 

22  82 

18.62 

23.12 

18.86 

23  41 

19.11 

47.2 

18.21 

22  59 

18.43 

22.88 

18.67 

23.18 

18.92 

23  47 

19.16 

47.3 

18.26 

22.66 

18.48 

22.94 

18.72 

23.24 

18.97 

23.64 

19.22 

47.4 

18.31 

22  72 

18.53 

23.01 

18.78 

23  31 

19.02 

23  60 

19.27 

47.5 

18.36 

22  78 

18.58 

23.07 

18.83 

23  37 

19.08 

23.67 

19.33 

47.6 

18.42 

22,84 

18.64 

23.13 

IS.  88 

23.44 

19.13 

23.73 

19.38 

47.7 

1   18.47 

22  91 

18.69 

23.20 

18.93 

23  50 

19.18 

23.80 

19.43 

47.8 

1   18.52 

22.97 

18.74 

23.26 

18.99 

23  66 

19.24 

23  86 

19.49 

47.9 

222 


METHODS    OF   ANALYSIS 


[Chap. 


6 

Table  17  — 

Alcoh 

17.5 

c. 

18° 

C. 

19° 

c. 

20° 

c. 

21°  C. 

SCALE 
READING 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  can 

by 

by 

by 

by 

by 

by 

by 

by 

by 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

volum 

48.0 

21.84 

17.80 

21  97 

17.91 

22.24 

18.14 

22  61 

18.36 

22.76 

48.1 

21.90 

17.85 

22  03 

17.96 

22.30 

18.19 

22.57 

18.41 

22  82 

48.2 

21.96 

17.90 

22  09 

18.01 

22.36 

18.24 

22  63 

18.46 

22.88 

48.3 

22  02 

17.95 

22.15 

18.06 

22.42 

18.29 

22  69 

18.51 

22.94 

48.4 

22.08 

18.00 

22.21 

18.11 

22.48 

18.34 

22.75 

18.56 

23.01 

48.5 

22  14 

18.05 

22  27 

18.16 

22.64 

18. S9 

22.81 

18.61 

23  07 

48.6 

22  20 

18.10 

22.33 

18.21 

22  60 

18.44 

22  87 

18.66 

23  13 

48.7 

22  26 

18.15 

22  39 

18.26 

22.66 

18.49 

22  93 

18.71 

23.19 

48.8 

22.32 

18.20 

22.45 

18.31 

22.72 

18.54 

22  99 

18.76 

23.26 

48.9 

22.38 

18.25 

22.61 

18.36 

22.78 

18.59 

23.06 

18.81 

23.32 

49.0 

22.44 

18. SO 

22  57 

18.41 

22.84 

18.64 

23.12 

18.86 

23.38 

49.1 

22.60 

18. S5 

22  63 

18.46 

22.90 

18.69 

23  18 

18.91 

23.44 

49.2 

22.56 

18.40 

22.69 

18.51 

22  96 

18.74 

23  24 

18.96 

23.51 

49.3 

22.62 

18.45 

22.75 

18.56 

23.02 

18.79 

23  30 

19.02 

23.57 

49.4 

22.68 

18.60 

22.81 

18.61 

23.08 

18.84 

23  36 

19.07 

23  63 

49.5 

22.74 

18.55 

22.87 

18.66 

23.15 

18.89 

23.42 

19.12 

23  69 

49.6 

22.80 

18.60 

22.93 

18.71 

23  21 

18.94 

23.48 

19.17 

23.76 

49.7 

22.86 

18.65 

22.99 

18.76 

23  27 

18.99 

23  66 

19.22 

23.82 

49.8 

22.92 

18.70 

23.05 

18.81 

23  33 

19.04 

23.61 

19.27 

23.88 

49.9 

22  98 

18.75 

23.11 

18.86 

23  39 

19.09 

23.67 

19.32 

23.94 

50.0 

23.04 

18.80 

23  17 

18.91 

23  45 

19.14 

23.73 

19.38 

24.01 

50.1 

23.10 

18.85 

23  23 

18.96 

23.51 

19.19 

23.79 

19.43 

24.07 

50.2 

23  16 

18.90 

23  30 

19.02 

23  57 

19.24 

23  86 

19.48 

24  13 

50.3 

23  22 

18.95 

23  36 

19.07 

23  63 

19.29 

23.91 

19.53 

24.19 

50.4 

23.28 

19.00 

23  42 

19.12 

23.69 

19.35 

23.98 

19.58 

24  26 

50.5 

23  34 

19.05 

23.48 

19.17 

23.76 

19.40 

24.04 

19.63 

24  32 

50.6 

23  40 

19.10 

23.54 

19.22 

23  81 

19.45 

24.10 

19.69 

24.38 

50.7 

23  46 

19.15 

23.60 

19.27 

23  87 

19.50 

24.16 

19.74 

24.45 

50.8 

23  51 

19.20 

23.66 

19.32 

23  93 

19.55 

24  22 

19.79 

24.51 

50.9 

23  57 

19.25 

23.72 

19.37 

23.99 

19.60 

24.28 

19.84 

24.57 

51.0 

23.63 

19. SO 

23.78 

19.42 

24.06 

19.65 

24  36 

19.89 

24.64 

51.1 

23.69 

19.35 

23.84 

19.47 

24.12 

19.70 

24.41 

19.94 

24.70 

51.2 

23  75 

19.40 

23  90 

19.52 

24.18 

19.75 

24  47 

20.00 

24.76 

51.3 

23.81 

19.45 

23.96 

19.57 

24  24 

19.80 

24.53 

20.05 

24.82 

51.4 

23  87 

19.50 

24.02 

19.62 

24.30 

19.85 

24.69 

20.10 

24  89 

51.5 

23  93 

19.55 

24  08 

19.67 

24.36 

19.90 

24.66 

20.15 

24.95 

51.6 

23.99 

19.60 

24.14 

19.72 

24.42 

19.95 

24.72 

20.20 

26.01 

51.7 

24.05 

19.65 

24.20 

19.77 

24.48 

20.01 

24.78 

20.26 

26.07 

51.8 

24.11 

19.70 

24.26 

19.82 

24.64 

20.06 

24.84 

20.  SI 

25.14 

51.9 

24.17 

19.75 

24.32 

19.87 

24.60 

20.11 

24.90 

20.36 

25.20 

52.0 

24  23 

19.80 

24.38 

19.92 

24.66 

20.16 

24.96 

20.41 

26.27 

52.1 

24.30 

19.85 

24.44 

19.97 

24.73 

20.21 

25.03 

20.46 

25.33 

52.2 

24.36 

19.90 

24.50 

20.02 

24.79 

20.26 

25.09 

20.52 

25  39 

52.3 

24.42 

19.95 

24.56 

20.07 

24.85 

20.31 

25.15 

20.57 

25.46 

52.4 

24.48 

20.00 

24.62 

20.12 

24.91 

20.37 

25,21 

20.62 

25.52 

52.5 

24.54 

20.05 

24.68 

20.17 

24.97 

20.42 

25.28 

20.67 

25.58 

52.6 

24.60 

20.10 

24.74 

20.22 

25.03 

20.47 

25.34 

20.72 

25.65 

52.7 

24.66 

20.15 

24.80 

20.28 

25.09 

20.52 

25.40 

20.78 

25.71 

52.8 

24.72 

20.20 

24.86 

20.83 

25.16 

20.57 

25.46 

20.83 

25.77 

52.9 

24.78 

20.25 

24.92 

20.38 

26.22 

20.62 

26.63 

20.88 

25.84 

XVI] 

WINES 

223 

Table. — Continued. 

6 

21°  C. 

22° 

c. 

23° 

C. 

24° 

C. 

25°  C. 

Per  cent 

by 
weight 

Per  cent 

by 
volume 

Per  cent 

by 

weight 

Per  cent 

by 
volume 

Per  cent 

by 
weight 

Per  cent 

by 
volume 

Per  cent 

by 
weight 

Per  cent 

by 
volume 

Per  cent 

by 
weight 

READING 

18.57 

18.62 

\   18.67 

■    18.72 

,    18.77 

23.03 
23.09 
23  16 
23  22 
23  28 

18.79 
18.84 
18.90 
18.95 
19.00 

23  32 
23  39 
23.45 
23.52 
23.58 

19.04 
19.09 
19.14 
19.20 
19.25 

23.63 
23.69 
23.76 
23  83 
23.89 

19.29 
19.34 
19.40 
19.45 
19.50 

23  93 
23.99 

24  06 
24.13 
24.19 

19.54 
19.60 
19.65 
19.71 
19.76 

48.0 
48.1 
48.2 
48.3 
48.4 

18.83 

18.88 

1   18.93 

1  18.98 

19.03 

23  35 
23.41 
23  47 
23  54 
23.60 

19.06 
19.11 
19.16 
19.21 
19.27 

23.64 
23  71 
23  77 
23.83 
23.90 

19.31 
19.36 
19.41 
19.47 
19.52 

23  96 

24  02 
24.08 
24.14 
24.21 

19.56 
19.61 
19.67 
19.72 
19.77 

24.26 
24.32 
24  39 
24.45 
24.52 

19.82 
19.87 
19.92 
19.98 
20.03 

48.5 
48.6 
48.7 
48.8 
48.9 

19.08 
19.14 
19.19 
:  19.24 
19.29 

23  66 
23  73 
23  79 
23  85 
23.92 

19.32 
19.37 
19.43 
19.48 
19.54 

23.96 
24.03 
24.09 
24.15 
24.22 

19.57 
19.63 
19.68 
19.73 
19.79 

24.27 
24.34 
24  40 
24.47 
24.53 

19.83 
19.88 
19.94 
19.99 
20.04 

24.59 
24  65 

24.72 
24.78 
24.85 

20.09 
20.15 
20.20 
20.26 
20.31 

49.0 
49.1 
49.2 
49.3 
49.4 

i  19.35 
1  19.40 
1  19.45 
;  19.61 
19.56 

23  98 

24  04 
24.11 
24  17 
24.24 

19.59 
19.64 
19.70 
19.75 
19.80 

24.28 
24  35 
24.41 
24.48 
24.54 

19.84 
19.89 
19.95 
20.00 
20.05 

24.60 
24.66 
24.73 
24.79 
24.86 

20.10 
20.15 
20.21 
20.27 
20.32 

24  91 
24.98 
25.05 
25.11 
25.18 

20.87 
20.42 
20.48 
20.54 
20.59 

49.5 
49.6 
49.7 
49.8 
49.9 

19.61 
i  19.66 
:  19.72 
•  19.77 

19.82 

24.30 
24  37 
24  43 
24.49 
24.66 

19.86 
19.91 
19.96 
20.02 
20.07 

24.61 
24.67 
24.74 
24.80 
24.86 

20.11 
20.16 
20.22 
20.27 
20.33 

24.92 
24.99 
25.05 
25.12 
25.18 

20.38 
20.43 
20.49 
20.54 
20.60 

25  25 
25.31 
25  38 
25.45 
25.51 

20.65 
20.70 
20.76 
20.82 
20.87 

50.0 
50.1 
50.2 
50.3 
50.4 

19.87 
19.93 
19.98 
80.03 
SO  08 

24.62 
24.69 
24.75 
24.81 
24.88 

20.12 
20.18 
20.23 
20.29 
20.34 

24.93 
24.99 
25.06 
25.12 
25.19 

20.38 

20.44 

20.49 
20.55 
20.60 

25.25 
25.32 
25  38 
25.45 
25  51 

20.65 
20.71 
20.76 
20.82 
20.87 

25  58 
25  65 
25.71 
25.78 
25.85 

20.93 
20.98 
21.04 
21.10 
21.15 

50.5 
50.6 
50.7 
50.8 
50.9 

JO.  14 
,20.19 

50.24 

24  94 
25.01 

25  07 
25.13 
25.20 

20.39 
20.45 
20.50 
20.55 
20.61 

25.25 
25  32 
25.38 
25.45 
25.51 

20.66 
20.71 
20.77 
20.82 
20.87 

25  58 
25.64 
25  71 
25.78 
25.84 

20. 9S 
20.98 
21.04 
21.09 
21.15 

25.91 

25  98 

26  05 
26.11 
26.18 

21.21 
21.27 
21.32 
21.S8 
21. U 

51.0 
51.1 
51.2 
51.3 
51.4 

.20.40 
20.46 

.20.51 
20.56 

\20.61 

25  26 
25  33 
25.39 
25.46 
25.52 

20.66 

20  72 
20.77 
20.82 
20.88 

25.58 
25  64 
25  71 
25.77 
25.84 

20.93 
20.98 
21.04 
21.09 
21.15 

25  91 

25  97 
26.04 

26  11 
26.17 

21.21 
21.26 
21.32 
21.37  . 
21.43 

26  25 
26  32 
26  39 
26  45 
26  52 

21.49 
21.55 
21.61 
21.66 
21.72 

51.5 
51.6 
51.7 
51.8 
51.9 

\i0.67 
\20.72 
20.77 
20.83 
.20.88 

25  58 
25  65 
25  71 
25.78 
25.84 

20.93 
20.98 
21.04 
21.09 
21.15 

25.90 
25.97 
26.03 
26.10 
26  16 

21.20 
21.26 
21.31 
21.37 
21.42 

26.24 
26  31 
26.37 
26.44 
26.51 

21.49 
21.54 
21.60 
21.65 
21.71 

26  59 
26  66 
26  72 
26  79 
26  86 

21.78 
21.83 
21.89 
21.95 
22.01 

52.0 
52.1 
52.2 
52.3 
52.4 

\20.9S 
'20.98 
\21.04 

\  2 1.00 
21.15 

25.90 
25.97 
26.03 
26.10 
26.16 

21.20 
21.26 
21.31 
21.36 
21.42 

26  23 
26.29 
26.36 
26.42 
26.49 

21.4S 
21.53 
21.59 
21.64 
21.70 

26.57 
26.64 
26  71 
26  77 
26.84 

21.77 
21.82 
21.88 
21.93 
21.99 

26.93 

26  99 

27  06 
27  13 
27  20 

22.06 
22.12 
22.18 
22.24 
22.29 

52.5 
52.6 
52.7 
52.8 
52.9 

1 

224 
6 


METHODS    OF   ANALYSIS 


[Chap. 


Table  17.— Alcoh 


17.5 

°C. 

18 

o. 

19' 

C. 

20 

C. 

21°  C. 

SCALE 
READING 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cen 

by 

by 

by 

by 

by 

by 

by 

by 

by 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

volum 

53.0 

24.84 

20.30 

24  98 

20.43 

25.28 

20.68 

25  59 

20.93 

25  90 

53.1 

24.90 

20.36 

25.04 

20.48 

25  34 

20.73 

25,65 

20.98 

25  96 

53.2 

24  96 

m.4i 

25  10 

20.53 

25.40 

20.78 

25,71 

21.04 

26  03 

53.3 

25  02 

20.46 

25,16 

20.58 

25.46 

20.83 

25,77 

21.09 

26  09 

53.4 

25.08 

20.51 

25.23 

20.63 

25.52 

20.88 

25,84 

21.14 

26.15 

53.5 

25.14 

20.56 

25  29 

20.68 

25.59 

20.93 

25  90 

21.20 

26.22 

53.6 

25  20 

20.61 

25  35 

20.74 

25.65 

20.98 

25  96 

21.25 

26  28 

53.7 

25  26 

20.66 

25.41 

20.79 

25.71 

21.04 

26  03 

21.30 

26  35 

53.8 

25  32 

20.71 

25,47 

20.84 

25.77 

21.09 

26  09 

21.36 

26.41 

53.9 

25  38 

20.76 

25  53 

20.89 

25  83 

21.14 

26,15 

21.41 

26  47 

54.0 

25.44 

20.81 

25,59 

20.94 

25  90 

21.19 

26  22 

21.47 

26  54 

54.1 

25  50 

20.86 

25,65 

20.99 

25.96 

21.25 

26  28 

21.52 

26  60 

54.2 

25  56 

20.91 

25  71 

21.04 

26  02 

21.30 

26  34 

21.57 

26  67 

54.3 

25  62 

20.96 

25  77 

21.09 

26  08 

21.35 

26,41 

21.63 

26  73 

54.4 

25  68 

21.02 

25,84 

21.14 

26.14 

21.40 

26.47 

21.68 

26  79 

54.5 

25.75 

21.07 

25  90 

21.20 

26  20 

21.46 

26  53 

21.73. 

26  86 

54.6 

25.81 

21.12 

25  96 

21.25 

26  27 

21.51 

26  59 

21.79 

26  92 

54.7 

25  87 

21.17 

26  02 

21.30 

26  33 

21.56 

26  66 

21.84 

26  99 

54.8 

25  93 

21.22 

26  08 

21.35 

26  39 

21.62 

26,72 

21.90 

27.05 

54.9 

26  99 

21.27 

26.14 

21.40 

26  45 

21.67 

26,78 

21.95 

27.11 

55.0 

26  05 

21.32 

26,20 

21.45 

26,52 

21.72 

26,85 

22.00 

27.18 

55.1 

26  11 

21.37 

26  26 

21.51 

26  58 

21.77 

26  91 

22.05 

27.24 

55.2 

26.17 

21.43 

26  32 

21.56 

26  64 

21.83 

26  97 

22.11 

27  31 

55.3 

26  23 

21.48 

26  38 

21.61 

26,70 

21.88 

27,04 

22.16 

27.37 

55.4 

26  29 

21.53 

26.45 

21.66 

26  76 

21.93 

27.10 

22.21 

27  43 

55.5 

26  35 

21.58 

26  51 

21.71 

26  83 

21.98 

27  16 

22.26 

27.49 

55.6 

26  41 

21.63 

26  57 

21.76 

26  89 

22.04 

27  23 

22.32 

27,55 

55.7 

26  47 

21.68 

26.63 

21.81 

26  95 

22.09 

27  29 

22.37 

27  62 

55.8 

26.53 

21.73 

26  69 

21.87 

27,01 

22.14 

27  35 

22.42 

27,69 

55.9 

26  59 

21.79 

26  75 

21.92 

27.07 

22.19 

27,41 

22.48 

27.75 

56.0 

26.65 

21.84 

26  81 

21.97 

27  14 

22.24 

27  48 

22.53 

27  82 

56.1 

26.72 

21.89 

26,87 

22.02 

27  20 

22.30 

27  54 

22.58 

27.88 

56.2 

26.78 

21.94 

26,93 

22.07 

27  26 

22.35 

27  60 

22.64 

27.94 

56.3 

26  84 

21.99 

26.99 

22.12 

27  32 

22.40 

27  66 

22.69 

28  01 

56.4 

26  90 

22.04 

27.05 

22.18 

27  38 

22.45 

27,73 

22.74 

28.07 

56.5 

26  96 

22.09 

27.12 

23.23 

27.44 

22.50 

27,79 

22.79 

28  14 

56.6 

27,02 

22.14 

27.18 

22.28 

27  51 

22.56 

27,85 

22.85 

28,20 

56.7 

27.08 

22.19 

27,24 

22.33 

27  57 

22.61 

27,91 

22.90 

28,26 

56.8 

27.14 

22.25 

27.30 

22.38 

27.63 

22.66 

27.98 

22.95 

28,33 

56.9 

27.20 

22.30 

27.36 

22.43 

27.69 

22.71  ' 

28.04 

23.01 

28  39 

57.0 

27.26 

22.35 

27.42 

22.48 

27  75 

22.77 

28.10 

23.06 

28  46 

57.1 

27  32 

22.40 

27  48 

22.54 

27  81 

22.82 

28.16 

23.11 

28  52 

57.2 

27  38 

22.45 

27.54 

22.59 

27.88 

22.87 

28.23 

23.17 

28  59 

57.3 

27.44 

22.50 

27.60 

22.64 

27.94 

22.92 

28.29 

23.22 

28  65 

57.4 

27  50 

22.55 

27.66 

22.69 

28.00 

22.97 

28  36 

23.27 

28.72 

57.5 

27.56 

22.61 

27.73 

22.74 

28.06 

23.03 

28.42 

23.33 

28.78 

57.6 

27  62 

22.66 

27.79 

22.79 

28.13 

23.08 

28.48 

23.38 

28  85 

57.7 

27.68 

22.71 

27.85 

22.85 

28.19 

23.13 

28.54 

23.43 

28  91 

57.8 

27.75 

22.76 

27.91 

22.90 

28.25 

23.19 

28.60 

23.49 

28  97 

57.9 

27.81 

22.81 

27.97 

22.95 

28.31 

23.24 

28.67 

23.54 

29.04 

XVI] 

WINES 

225 

|TABLE. — Continued. 

6 

j      21- C. 

22 

C. 

23 

c. 

24 

c. 

25 

'C. 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

SCALE 
READING 

by 

by 

by 

by 

by 

by 

by 

by 

by 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

1  - 

'    SI. 20 

26  23 

21.47 

26.56 

21.75 

26  91 

22.05 

27  27 

22.35 

53.0 

SI  .25 

26  29 

21.53 

26.62 

21.81 

26  97 

22.10 

27  33 

22.41 

53.1 

.   SI. 31 

26  35 

21.58 

26  69 

21.86 

27.04 

22.16 

27.40 

22.47 

53.2 

1  S1.S6 

26  42 

21.64 

26.75 

21.92 

27.11 

22.22 

27  47 

22.52 

53.3 

'  SI. 42 

26  48 

21.69 

26  82 

21.97 

27.17 

22.27 

27  64 

22.58 

53.4 

1 
SI.  47 

26  55 

21.74 

26  88 

2,2 .  03 

27  24 

22.33 

27  61 

22.64 

53.5 

SI.  52 

26  61 

21.80 

26  95 

22.08 

27  31 

22.39 

27  67 

22.70 

53.6 

S1.5R 

26  68 

21.85 

27.01 

22.14 

27.38 

22.44 

27.74 

22.75 

53.7 

SI  68 

26  74 

21.91 

27  08 

22.20 

27.44 

22.50 

27  81 

22.81 

53.8 

SI. 69 

26  81 

21.96 

27  15 

22.25 

27  51 

22.56 

27.88 

22.87 

53.9 

SI. 7  4 

26  87 

22.02 

27  21 

22.31 

27  58 

22.61 

27  95 

22.93 

54.0 

SI. 79 

26  94 

22.07 

27  28 

22.37 

27  64 

22.67 

28  01 

22.98 

54.1 

'  SI. 85 

27  00 

22.13 

27  35 

22.42 

27  71 

22.73 

28  08 

23.04 

54.2 

•  SI. 90 

27  07 

22.18 

27  41 

22.48 

27.78 

22.78 

28.15 

23.10 

54.3 

1  SI. 96 

27  13 

22.24 

27  48 

22.53 

27.85 

22.84 

28.22 

28.16 

54.4 

\  SS.Ol 

27  20 

22.29 

27  55 

22.59 

27  91 

22.90 

28  29 

23.22 

54.5 

'  S2.06 

27  26 

22.35 

27.61 

22.65 

27  98 

22.95 

28  36 

23.27 

54.6 

I  S2.12 

27  33 

22.40 

27  68 

22.70 

28  05 

28.01 

28  43 

23.33 

54.7 

1  SS.17 

27  39 

22.46 

27.75 

22.76 

28  11 

23.07 

28  49 

23  39 

54.8 

1  S2.23 

27  46 

22.51 

27  81 

22.81 

28.18 

23.13 

28  56 

28.45 

54.9 

j  2S.28 

27  52 

22.57 

27  88 

22.87 

28  26 

23.18 

28  63 

23.51 

55.0 

SS.S3 

27  59 

22.63 

27  95 

22.93 

28  32 

28.24 

28  70 

28.56 

55.1 

tS.S9 

27  65 

22.68 

28  01 

22.98 

28  38 

23.30 

28.77 

23.62 

55.2 

SS.44 

27.72 

22.74 

28.08 

23.04 

28  45 

28.35 

28  84 

23.68 

55.3 

SS.49 

27  78 

22.79 

28  15 

23.10 

28.52 

28.41 

28  90 

23.74 

55.4 

SS.55 

27  85 

22.85 

28  21 

23.15 

28  58 

23.47 

28  97 

23.80 

55 . 5 

i  SS.60 

27  92 

22.90 

28  28 

23.21 

28  65 

23.63 

29.04 

23.86 

55.6 

'  S2.66 

27  98 

22.96 

28  34 

28  26 

28.72 

23.58 

29  11 

23.91 

55.7 

•  ?■?  71 

28  05 

23.01 

28  41 

23.32 

28.78 

23.64 

29  18 

23.97 

55.8 

7f> 

28.11 

23.07 

28.48 

23.38 

28.85 

23.70 

29  24 

24.03 

55.9 

'  ^2 

28  18 

23.12 

28.54 

23.43 

28.92 

23.75 

29  31 

24.09 

56.0 

■  22.S7 

28  24 

23.18 

28.61 

23.49 

28  99 

23.81 

29  38 

24.14 

56.1 

1  S2.92 

28  31 

23.23 

28.68 

23.54 

29  05 

23.87 

29.45 

24.20 

56.2 

00  0,9 

28  37 

23.29 

28.74 

23.60 

29.12 

23.93 

29.52 

24.26 

56.3 

■   ■'.? 

28.44 

23.34 

28  81 

23.66 

29  19 

23.98 

29  58 

24.32 

56.4 

-•)  09 

28  50 

23.40 

28  87 

23.71 

29  26 

24.04 

29  65 

24.38 

50.5 

■  SS.14 

28.56 

23.45 

28.94 

23.77 

29  32 

24.10 

29.72 

24.4s 

56.6 

'  Sf!.20 

28  63 

23.51 

29  01 

23.88 

29  39 

24.15 

29  79 

24.49 

56.7 

""  ^5 

28.69 

23.56 

29  07 

23.88 

29.46 

24.21 

29  86 

24.55 

56.8 

;/ 

28  76 

23.62 

29  14 

23.94 

29.53 

24.27 

29  93 

24. 61 

56.9 

7? 

28  82 

23.67 

29.20 

23.99 

29  59 

24.32 

29  99 

24.66 

57.0 

■•) 

28  89 

23.73 

29  27 

24.05 

29  66 

24.38 

30  06 

24.72 

57.1 

'- 

28  95 

23.78 

29  34 

24.11 

29  73 

24-44 

30  13 

24.78 

55.2 

,  .*S.5l' 

29  02 

23.84 

29  40 

24.16 

29  80 

24.49 

30  20 

24.84 

55.3 

!  SS.5S 

29  08 

23.90 

29.47 

24.22 

29.86 

24.55 

30  27 

24.90 

57.4 

'  SS.63 

29  15 

23.95 

29  53 

24.27 

29  93 

24.61 

30  34 

24.95 

57.5 

\  2S.69 

29  21 

24.01 

29.60 

24.33 

30  00 

24.66 

30.41 

25.01 

57.6 

1  iS.74 

29.28 

24.06 

29.66 

24.39 

30.07 

24.72 

30  48 

25.07 

57.7 

1  W.80 

29.34 

24.12 

29.73 

24.44 

30.14 

24.78 

30.66 

25. IS 

57.8 

'  SS.85 

29  41 

24.17 

29.80 

24.50 

30.20 

24.8S 

30.62 

25.19 

57.9 

1 

226 

METHODS    OF   ANALYSIS 

1 
[Chap. 

6 

Table  17.— 

AlcohoiI 

17.5 

°C. 

18 

C. 

19 

c. 

20 

c. 

21°  C. 

SCALE 
READINO 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

by 

by 

by 

by 

by 

by 

by 

by 

by 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

58.0 

27  87 

22.86 

28,03 

23.00 

28.38 

23.29 

28  73 

23.59 

29.10 

68.1 

27  93 

22.91 

28  09 

23.05 

28.44 

23.34 

28.79 

23.65 

29.17 

58.2 

27.99 

22.96 

28,15 

23.10 

28  50 

23.40 

28  86 

23.70 

29.23 

58.3 

28  05 

23.02 

28,21 

23.16 

28.56 

23.45 

28  92 

23.75 

29  29 

58.4 

28.11 

23.07 

28,28 

23.21 

28.62 

23.50 

28.98 

23.81 

29.36 

58.5 

28.17 

23.12 

28.34 

23.26 

28,69 

23  56 

29,04 

23.86 

29  42 

58.6 

28  23 

23.17 

28,40 

23.31 

28  75 

23.61 

29,11 

23.91 

29.48 

58.7 

28.29 

23.22 

28  46 

23.36 

28,81 

23.66 

29,17 

23.97 

29  55 

58.8 

28  35 

23.27 

28  62 

23.41 

28,88 

23.71 

29  23 

24.02 

29.61 

58.9 

28.41 

23.32 

28,58 

23.47 

28.94 

23.77 

29  30 

24. 08 

29.68 

59.0 

28  47 

23.37 

28,64 

23.52 

29  00 

23.82 

29  36 

24.1s 

29  74 

59.1 

28,63 

23.43 

28,71 

23.57 

29  06 

23.87 

29,42 

24. 18 

29  80 

59.2 

28  69 

23.48 

28,77 

23.62 

29.12 

23.93 

29,49 

24.24 

29  87 

59.3 

28  65 

23.53 

28.83 

23.67 

29.19 

23.98 

29,55 

24.29 

29  93 

59.4 

28.71 

23.58 

28.89 

23.73 

29.25 

24-03 

29.61 

24.34 

29,99 

59.5 

28.78 

23.63 

28.95 

23.78 

29  31 

24-08 

29  68 

24.40 

30  06 

59.6 

28  84 

23.68 

29.01 

23.83 

29  37 

24-14 

29.74 

24.45 

30  13 

59.7 

28  90 

23.73 

29,07 

23.88 

29.43 

24-19 

29  80 

24.50 

30  19 

59.8 

28  96 

23.79 

29  13 

23.93 

29  50 

24-24 

29.87 

24.56 

30  26 

59.9 

29,02 

23.84 

29  20 

23.98 

29  56 

24-30 

29.93 

24. 61 

30  32     . 

60.0 

29,08 

23.89 

29  26 

24.04 

29,62 

24-35 

29  99 

24.67 

30.39 

60.1 

29,14 

23.94 

29  32 

24.09 

29  68 

24.40 

30  06 

24.72 

30  45     ' 

60.2 

29,20 

23.99 

29  38 

H.I4 

29,74 

24.46 

30  12 

24.77 

30  52 

60.3 

29,26 

24.04 

29  44 

24.19 

29,81 

24-51 

30  19 

24.83 

30  59 

60.4 

29,32 

24.10 

29  60 

24.25 

29,87 

24-56 

30.26 

24.88 

30  65 

60.5 

29  38 

24.15 

29  56 

24.30 

29.93 

24-61 

30  32 

24.94 

30  72 

60.6 

29  45 

24.20 

29  63 

24.35 

29  99 

24-67 

30.38 

24.99 

30  78 

60.7 

29  51 

24.25 

29  69 

24.40 

30  06 

24-72 

30.46 

25.04 

30  85 

60.8 

29  57 

24.30 

29  75 

24.46 

30.12 

24-77 

30.61 

25.10 

30  91 

60,9 

29,63 

24-35 

29.81 

24.51 

30.18 

24-83 

30  67 

25.16 

30  98 

61.0 

29,69 

24.41 

29  87 

24.56 

30  26 

24-88 

30,64 

25.21 

31  05 

61.1 

29  75 

24.48 

29  93 

24-61 

30.31 

24.93 

30  70 

25.27 

31  11 

61.2 

29,81 

24-51 

29  99 

24.66 

30  38 

24.98 

30  77 

25.32 

31  18 

61.3 

29  87 

24.56 

30  06 

24-72 

30.44 

25.04 

30  83 

25.38 

31  25 

61.4 

29,93 

24. 61 

30  12 

24-77 

30.50 

25.09 

30  90 

25.44 

31  32 

61.5 

29  99 

24.67 

30  18 

24-82 

30  67 

25.15 

30,98 

25.49 

31  39 

61.6 

30  06 

24.72 

30  25 

24-87 

30.63 

25.20 

31.03 

25.55 

31  45 

61.7 

30,12 

24.77 

30  31 

24.93 

30.69 

25.26 

31  09 

25.60 

31  52 

61.8 

30,18 

24.82 

30  37. 

24-98 

30  76 

25.31 

31,16 

25.66 

31.59 

61.9 

30,25 

24.88 

30,44 

25.03 

30.82 

25.37 

31,23 

25.71 

31,66 

62.0 

30  31 

24.93 

30  50 

25.09 

30  89 

25.43 

31.29 

25.77 

31  72 

62.1 

30  37 

24.98 

30  56 

25.14 

30.96 

25.48 

31  36 

25.83 

31  79 

62.2 

30,43 

2>.0S 

30  63 

25.20 

31  01 

25.54 

31  43 

25.88 

31  86 

62.3 

30,60 

25.09 

30  69 

25.25 

31  08 

25.59 

31  49 

25.94 

31  93 

62.4 

30.66 

25.14 

30  75 

25.31 

31.14 

25.65 

31  66 

25.99 

31,99 

62.5 

30  62 

25.20 

30  82 

25.36 

31  21 

25.70 

31  63 

26.05 

32  06 

62.6 

30  69 

25.25 

30  88 

25.42 

31.28 

25.76 

31  69 

26.11 

32  13 

62,7 

30.75 

2-5.31 

30  94 

25.47 

31.34 

25.81 

31,76 

26.17 

32  20 

62.8 

30  81 

25.36 

31  01 

25.53 

31.41 

25.87 

31  83 

26.23 

32  27 

62.9 

30.87 

25.42 

31,07 

25.58 

31.47 

25.92 

31,89 

26.29 

32.34 

1 

XVI] 


Dable. — Continued. 


227 
6 


21°C. 

22 

•c. 

23 

C. 

24 

C. 

25 

C. 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

BCALB 
READINO 

by 

by 

by 

by 

by 

by 

by 

by 

by 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

S3. 91 

29.47 

24.23 

29.87 

24.55 

30  27 

24.89 

30  69 

25.25 

58.0 

23.96 

29.54 

24-28 

29.93 

24. 61 

30.34 

24.95 

30  76 

25.31 

58.1 

2^.02 

29  60 

24.34 

29.99 

24.66 

30.41 

25.01 

30  83 

25.37 

58.2 

U.07 

29.67 

24.39 

30.06 

24.72 

30.48 

25.07 

30.90 

25.43 

58.3 

24.13 

29.73 

24.45 

30.13 

24.78 

30.54 

25.13 

30.97 

25.49 

58.4 

24.18 

29  80 

24-50 

30  20 

24.83 

30.61 

25.18 

31  04 

25.55 

58.5 

24.23 

29.86 

24-56 

30  26 

24.89 

30.68 

25.23 

31.11 

25.61 

58.6 

24.29 

29  93 

24-61 

30  33 

24.94 

30.75 

25.29 

31.18 

25.67 

58.7 

24.34 

29.99 

24-67 

30.40 

25.00 

30  82 

25.35 

31.25 

25.73 

58.8 

24.40 

30.06 

24-72 

30.47 

25.06 

30.88 

25.41 

31.32 

25.80 

58.9 

24.45 

30  13 

24.78 

30.53 

25.12 

30.95 

25.47 

31  40 

25.86 

59.0 

24.51 

30.19 

24-83 

30  60 

25.18 

31.02 

25.53 

31.47 

25.92 

59.1 

24-56 

30.26 

24-89 

30.67 

25.24 

31.09 

25.59 

31.54 

25.98 

59.2 

24.61 

30  33 

24.95 

30.74 

25.30 

31.16 

25.65 

31  61 

26.04 

59.3 

24.67 

30  39 

25.00 

30  81 

25.36 

31  23 

25.71 

31.68 

26.10 

59.4 

24-72 

30.46 

25.06 

30.87 

25.41 

31.30 

25.77 

31.76 

26.16 

59.5 

24-78 

30  53 

25.11 

30.94 

25.47 

31  38 

25.83 

31  83 

26.23 

59.6 

24-83 

30.59 

25.17 

31.01 

25.53 

31  45 

25.89 

31  90 

26.29 

59.7 

24-89 

30.66 

25.23 

31.08 

25.59 

31.52 

25.95 

31.97 

26.35 

59.8 

24.94 

30  73 

25.29 

31.15 

25.65 

31.59 

26.02 

32  04 

26.42 

59.9 

24.99 

30  79 

25.84 

31.22 

25.71 

31.66 

26.08 

32.12 

26.48 

60.0 

25.05 

30  86 

25.40 

31.29 

25.77 

31  73 

26.14 

32.19 

26.54 

60.1 

25.11 

30  93 

25.46 

31  36 

25.83 

31  80 

26.20 

32.27 

26.61 

60.2 

25.16 

30  99 

25.52 

31.43 

25.89 

31  87 

26.27 

32  34 

26.67 

60.3 

25.22 

31.06 

25.57 

31.60 

25.95 

31  94 

26.33 

32  41 

26.73 

60.4 

25.28 

31  13 

25.63 

31.57 

26.01 

32  02 

26.39 

32  49 

26.80 

60.5 

25.34 

31  20 

25.69 

31.64 

26.07 

32  09 

26.45 

32.56 

26.86 

60.6 

25.59 

31  27 

25.75 

31.71 

26.13 

32  16 

26.52 

32.64 

26.92 

60.7 

25.45 

31  33 

25.80 

31.78 

26.19 

32  23 

26.58 

32.71 

26.99 

60.8 

25.51 

31.40 

25.86 

31.85 

26.25 

32.30 

26.64 

32.78 

27.05 

60.9 

25.56 

31  47 

25.92 

31.92 

26. SI 

32  38 

26.70 

32  86 

27  12 

61.0 

25.62 

31  54 

25.98 

31.99 

26.37 

32  45 

26.76 

32.93 

27.18 

61.1 

25.68 

31  61 

26.04 

32.06 

26.43 

32.52 

26.83 

33  01 

27.24 

61.2 

25.73 

31.67 

26.10 

32.13 

26.49 

32  59 

26.89 

33  08 

27.31 

61.3 

25.79 

31.74 

26.16 

32.20 

26.55 

32.67 

26.95 

33  16 

27.37 

61.4 

25.85 

31  81 

26.22 

32.27 

26.61 

32  74 

27.01 

33  23 

27. U 

61.5 

25.90 

31  88 

26.28 

32  34 

26.67 

32  81 

27.08 

33  31 

27.50 

61.6 

25.96 

31.95 

26.34 

32.41 

26.73 

32.88 

27.14 

33  38 

27.56 

61.7 

26.02 

32.01 

26.40 

32.49 

26.79 

32.96 

27.20 

33  46 

27.63 

61.8 

26.08 

32  09 

26.46 

32.56 

26.85 

33  03 

27.27 

33  53 

27.69 

61.9 

26.14 

32.16 

26.51 

32  63 

26.92 

33  10 

27.33 

33  60 

27.76 

62.0 

26.20 

32.23 

26.57 

32.70 

26.98 

33  18 

27.39 

33  68 

27.82 

62.1 

26.25 

32  30 

26.63 

32.77 

27.04 

33  25 

27.46 

33.75 

27.88 

62.2 

26.31 

32  37 

26.69 

32.84 

27.10 

33  33 

27.52 

33  83 

27.95 

62.3 

26.37 

32.44 

26.75 

32.91 

27.16 

33.40 

27.58 

33  90 

28.01 

62.4 

26.43 

32.51 

26.81 

32.99 

27.23 

33  47 

27.65 

33  98 

28.08 

62.5 

26.49 

32.68 

26.87 

33  06 

27  29 

33.55 

27.71 

34  05 

28.15 

62.6 

26.55 

32.65 

26.93 

33.13 

h'.h 

33.62 

27.77 

34  13 

28.22 

62.7 

26.61 

32.72 

26.99 

33.20 

27.41 

33.70 

27.84 

34  21 

28.28 

62.8 

26.67 

32.79 

27.06 

33.28 

27.48 

33.77 

27.90 

34  29 

28.35 

62.9 

228 

METHODS    OF   ANALYSIS 

[Chap. 

6 

Table  17.- 

Alcohol 

17.5 

-c. 

18° 

C. 

19 

c. 

20° 

c. 

21°  c 

SCALE 
READING 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

by 

by 

by 

by 

by 

by 

by 

by 

by 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

63.0 

30  94 

2547 

31.14 

25.64 

31.54 

25.98 

31.96 

26.35 

32.41 

63.1 

31  GO 

25.52 

31  20 

25.69 

31.61 

26.03 

32.03 

26.41 

32  48 

63.2 

31  06 

25.58 

31  26 

25.75 

31.67 

26.09 

32.10 

26.46 

32  55 

63.3 

31  13 

25.63 

31  33 

25.80 

31  74 

26.15 

32  17 

26.52 

32.62 

63.4 

31  19 

25.69 

31  39 

25.86 

31  80 

26.21 

32  23 

26.58 

32  69 

63.5 

31.26 

25.74 

31.46 

25.91 

31  87 

26.26 

32  30 

26.64 

32  76 

63.6 

31  32 

25.80 

31.52 

25.97 

31  93 

26.32 

32  37 

26.70 

32  83 

63.7 

31  38 

25.85 

31.59 

26.02 

32  00 

26.38 

32.44 

26.76 

32.90 

63.8 

31  45 

25.91 

31  65 

26.08 

32  07 

26.44 

32  51 

26.82 

32.97 

63.9 

31  51 

25.96 

31  72 

26.13 

32  13 

26.49 

32  58 

26.88 

33  04 

64.0 

31  58 

26.02 

31  78 

26.19 

32  20 

26.55 

32  66 

26.94 

33  11 

64.1 

31  64 

26.07 

31  85 

26.25 

32  27 

26.61 

32  72 

26.99 

33  18 

64.2 

31  70 

26.13 

31.91 

26.30 

32  34 

26.67 

32  79 

27.05 

33  25 

64.3 

31  77 

26.18 

31  97 

26.36 

32.40 

26.72 

32  86 

27.11 

33  32 

64.4 

31  83 

26.24 

32.04 

26.41 

32.47 

26.78 

32  92 

27.17 

33  39 

64.5 

31  90 

26.29 

32  11 

26.47 

32.54 

26.84 

32  99 

27.23 

33.46 

64.6 

31  96 

26.35 

32.17 

26.53 

32.60 

26.90 

33  06 

27.29 

33  53 

64.7 

32  03 

26.40 

32.24 

26.58 

32.67 

26.95 

33  13 

27.35 

33  60 

64.8 

32  09 

26.46 

32.30 

26.64 

32  74 

27.01 

33  20 

27.41 

33.67 

64.9 

32  16 

26.51 

32  37 

26.69 

32  81 

27.07 

33  27 

27.47 

33.74 

65.0 

32  22 

26.57 

32  43 

26.75 

32  87 

27.13 

33  34 

27.53 

33  82 

65.1 

32  29 

26.63 

32.50 

26.80 

32.94 

27.19 

33  41 

27.59 

33  89 

65.2 

32  35 

26.68 

32  57 

26.86 

33.01 

27.25 

33.48 

27.65 

33.96 

65.3 

32  42 

26.74 

32  63 

26.92 

33  08 

27.31 

33  55 

27.71 

34  03 

65.4 

32  48 

26.79 

32  70 

26.97 

33  15 

27.37 

33  62 

27.77 

34  10 

65.5 

32  55 

26.85 

32.76 

27.03 

33  22 

27.43 

33  69 

27.83 

34.18 

65.6 

32  61 

26.90 

32  83 

27.09 

33  28 

27.49 

33  76 

27.89 

34  25 

65.7 

32  68 

26.96 

32.89 

27.15 

33  35 

27.54 

33  83 

27.95 

34.32 

65.8 

32  75 

27.01 

32  96 

27.21 

33  42 

27.60 

33.90 

28.01 

34  40 

65.9 

32.81 

27.07 

33  03 

27.26 

33  49 

27.66 

33  97 

28.07 

34.47 

66.0 

32.88 

27.13 

33.10 

27.32 

33  56 

27.72 

34.04 

28.13 

34.54 

66.1 

32.94 

27.19 

33  17 

27.38 

33  63 

27.78 

34.11 

28.19 

34.62 

66.2 

33  01 

27.25 

33  23 

27.44 

33  70 

27.84 

34.18 

28.26 

34.69 

66.3 

33  07 

27.30 

33  30 

27.50 

33  77 

27.90 

34.25 

28.32 

34.76 

66.4 

33  14 

27.36 

33  37 

27.56 

33  84 

27.96 

34  33 

28.38 

34.84 

66.5 

33.21 

27.42 

33  44 

27.62 

33.91 

28.02 

34.40 

28.45 

34  91 

66.6 

33  28 

27.48 

33  51 

27.68 

33.98 

28.08 

34.47 

28.51 

34.99 

66.7 

33  35 

27.54 

33  58 

27.73 

34  05 

28.14 

34.54 

28.57 

35  06 

66.8 

33  41 

27.60 

33  65 

27.79 

34  12 

28.20 

34.62 

28.64 

35.14 

66.9 

33  48 

27.65 

33  72 

27.85 

34.19 

28.27 

34.69 

28.70 

35  21 

67.0 

33  55 

27.71 

33  79 

27.91 

34  26 

28.33 

34.76 

28.76 

35  29 

67.1 

33  62 

27.77 

33  86 

27.97 

34.34 

28.39 

34.83 

28.82 

36  37 

67.2 

33  69 

27.83 

33  92 

28.03 

34.41 

28.45 

34.91 

28.89 

35  44 

67.3 

33.76 

27.89 

33.99 

28.09 

34  48 

28.52 

34.98 

28.95 

35.52 

67.4 

33  82 

27.95 

34  06 

28.15 

34  55 

28.58 

35  05 

29.01 

35  60 

67.5 

33  89 

28.01 

34  13 

28.21 

34.62 

28.64 

35.13 

29.08 

35  67 

67.6 

33  96 

28.06 

34.20 

28.27 

34.69 

28.70 

35  20 

29.14 

35.75 

67.7 

34  03 

28.12 

34.27 

28.34 

34.76 

28.76 

35.28 

29.21 

36.82 

67.8 

34.09 

28.18 

34.34 

28.40 

34.84 

28.83 

35  35 

29.27 

35  90 

67.9 

34  16 

28.24 

34  41 

28.46 

34.91 

28.89 

35.43 

29.34 

35.98 

XVI] 


Table. — Continued. 


229 
6 


21°  C. 

22° 

C. 

23° 

C. 

24° 

c. 

25 

C. 

Per  cent 

by 
weight 

Per  cent 

by 
volume 

Per  cent 

by 
weight 

Per  cent 

by 
volume 

Per  cent 

by 
weight 

Per  cent 

by 
volume 

Per  cent 

by, 

weight 

Per  cent 

by 
volume 

Per  cent 

by 
weight 

SCAJCE 
RE.VDINQ 

i6.73 

32  87 

27.12 

33  35 

27.54 

33  84 

27.96 

34  36 

28.42 

63.0 

J16.79 

32.94 

27.18 

33  42 

27.60 

33  92 

28.03 

34.44 

28.49 

63.1 

£6.85 

33  01 

27.24 

33.50 

27.66 

33  99 

28.09 

34  52 

28.55 

63.2 

26.91 

33  08 

27.31 

33  57 

27.72 

34.07 

28.16 

34.60 

28.62 

63.3 

26.96 

33  15 

27.37 

33  64 

27.79 

34.15 

28.23 

34.67 

28.69 

63.4 

27.02 

33  22 

27.43 

33  72 

27.85 

34  22 

28.29 

34  75 

28.76 

63.5 

27.09 

33  30 

27.49 

33  79 

27.91 

34  30 

28.36 

34.83 

28.82 

63.6 

27.15 

33  37 

27.56 

33.86 

27.98 

34  38 

28.43 

34  91 

28.89 

63.7 

27.  ei 

33  44 

27.62 

33  93 

28.04 

34.46 

28.49 

34  98 

28.96 

63.8 

27.27 

33  51 

27.68 

34.01 

28.11 

34  53 

28.56 

35  07 

29.03 

63.9 

27.38 

33  59 

27.74 

34.08 

28.17 

34  61 

28.63 

35  15 

29.10 

64.0 

27.39 

33  66 

27.81 

34.16 

28.24 

34  68 

28.69 

35  23 

29.17 

64.1 

27.45 

33  73 

27.87 

34  23 

28.30 

34.76 

28.76 

35  31 

29.24 

64.2 

27.51 

33  80 

27.93 

34  31 

28.37 

34.84 

28.83 

35  39 

29.31 

64.3 

27.57 

33  88 

27.99 

34  39 

28.43 

34  92 

28.89 

35  48 

29.38 

64.4 

27.63 

33  95 

28.06 

34.46 

28.50 

34  99 

28.96 

35  56 

29.45 

64.5 

27.70 

34  02 

28.12 

34.54 

28.57 

35  07 

29.03 

35  64 

29.52 

64.6 

27.76 

34  10 

28.19 

34.61 

28.63 

35  15 

29.10 

35.72 

29.60 

64.7 

27.82 

34.17 

28.25 

34  69 

28.70 

35.23 

29.17 

35  80 

29.67 

64.8 

27.88 

34.24 

28.31 

34.76 

28.76 

35  31 

29.24 

35.89 

29.74 

64.9 

27.94 

34  32 

28.38 

34  84 

28.83 

35  39 

29.31 

35  97 

29.81 

65.0 

28.00 

34  39 

28.44 

34.92 

28.89 

35.47 

29.38 

36  05 

29.88 

65.1 

28.06 

34.47 

28.51 

34  99 

28.96 

35  55 

29.44 

38  13 

29.95 

65.2 

28.13 

34  54 

28.57 

35  07 

29.03 

35  63 

29.51 

36  21 

30.02 

65.3 

28.19 

34  61 

28.63 

35.15 

29.10 

35.71 

29.58 

36  30 

30.10 

65.4 

28.25 

34.69 

28.70 

35  23 

29.16 

35.79 

29.65 

36  38 

30.17 

65.5 

28.32 

34  76 

28.76 

35  30 

29.23 

35  87 

29.72 

36  46 

30.24 

65.6 

28.38 

34.84 

28.83 

35  38 

29.30 

35  94 

29.79 

36  55 

30.32 

65.7 

28.45 

34  91 

28.89 

35  46 

29.37 

36  02 

29.86 

36  63 

30.39 

65.8 

88.51 

34  99 

28.96 

35  54 

29.44 

36.11 

29.93 

36.71 

30.46 

65.9 

28.57 

35  06 

29.02 

35  62 

29.51 

36  19 

30.00 

36  79 

30.54 

66.0 

28.64 

35  14 

29.09 

35  70 

29.58 

36  27 

30.07 

36  88 

30.61 

66.1 

28.70 

35  22 

29.16 

35.77 

29.64 

36  35 

30.15 

36  96 

30.68 

66.2 

28.76 

35  30 

29.23 

35  85 

29.71 

36  43 

30.22 

37  04 

30.76 

66.3 

28.83 

35  38 

29.29 

35  93 

29.78 

36.52 

30.29 

37  13 

30.83 

66.4 

28.89 

35  45 

29.36 

36  01 

29.85 

36.60 

30.36 

37  22 

30.90 

66.5 

28.96 

35  53 

29.43 

36  09 

29.92 

36  68 

30.43 

37  30 

30.98 

66.6 

29.03 

35  61 

29.50 

36.17 

29.99 

36.76 

30.51 

37  39 

31.05 

66.7 

29.09 

35  69 

29.57 

36.25 

30.06 

36  84 

30.58 

37  48 

31.13 

66.8 

29.15 

35.77 

29.64 

36  33 

30.13 

36  93 

30.65 

37  57 

31.21 

66.9 

29.22 

35  84 

29.71 

36  41 

30.20 

37.01 

30.72 

37  65 

31.28 

67.0 

29.29 

35  92 

29.77 

36  49 

30.27 

37  09 

30.80 

37  74 

31.36 

67.1 

29.35 

36  00 

29.84 

36  57 

30.34 

37  18 

30.87 

37  83 

31. U 

67.2 

29.42 

36.08 

29.91 

36  65 

30.41 

37.26 

30.94 

37.91 

31.51 

67.3 

29.49 

36  16 

29.98 

36  73 

30.49 

37  35 

31.02 

38  00 

31.59 

67.4 

29.55 

36  24 

30.05 

36  81 

30.56 

37.44 

31.09 

38  09 

31.65 

67.5 

29.62 

36  32 

SO.  12 

36.90 

30.63 

37.52 

31.17 

38  18 

31.74 

67.6 

29.69 

36  40 

30.19 

36  98 

30.70 

37.61 

31.24 

38  26 

31.82 

67.7 

29.75 

36  48 

30.26 

37  06 

30.77 

37  69 

31.32 

38  35 

31.89 

67.8 

29.82 

36.56 

30.33 

37.14 

30.84 

37.78 

31.39 

38.44 

31.97 

67.9 

230 

METHODS    OF   ANALYSIS 

[Chap. 

6 

Table  17  — 

-Alcghq] 

17.5 

°C. 

18° 

C. 

19° 

c. 

20° 

c. 

21°  C. 

SCALE 
READING 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

by 

by 

by 

by 

by 

by 

by 

by 

by 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

68.0 

34.23 

28.30 

34.48 

28.52 

34.98 

28.95 

35  60 

29.41 

36  06 

68.1 

34.30 

28.36 

34.55 

28.58 

35  05 

29.01 

35  57 

29.47 

36.13 

68.2 

34.36 

28.42 

34.62 

28.64 

35.13 

29.08 

35.65 

29.54 

36  21 

68.3 

34  43 

28.48 

34.69 

28.70 

35.20 

29.14 

35.72 

29.60 

36.29 

68.4 

34.50 

28.54 

34.76 

28.76 

35.27 

29.21 

35.80 

29.67 

36  37 

68.5 

34.57 

28.59 

34.83 

28.82 

35  35 

29.27 

35  87 

29.73 

36  46 

68.6 

34.64 

28.65 

34.90 

28.88 

35.42 

29.33 

36.96 

29.80 

36.62 

68.7 

34.70 

28.71 

34.97 

28.95 

35.49 

29.40 

36.02 

29.86 

36  60 

68.8 

34.77 

28.77 

35  04 

29.01 

35.57 

29.46 

36.10 

29.93 

36.68 

68.9 

34.84 

28.83 

35  12 

29.07 

35.64 

29.53 

36.18 

29.99 

36.76 

69.0 

34  91 

28.89 

35.19 

29.13 

35.71 

29.59 

36.26 

30.06 

36.84 

69.1 

34.97 

28.95 

35.26 

29.19 

35.79 

29.65 

36  33 

30.13 

36.91 

69.2 

35  04 

29.01 

35  33 

29.26 

35.86 

29.72 

36.41 

30.20 

36  99 

69.3 

35.12 

29.07 

35.40 

29.32 

35  93 

29.78 

36.48 

30.27 

37.07 

69.4 

35  19 

29.14 

35.47 

29.38 

36.01 

29.85 

36.66 

30.33 

37.16 

69.5 

35.27 

29.20 

35  56 

29.45 

36.08 

29.91 

36.64 

30.40 

37.24 

69.6 

35  34 

29.26 

35.62 

29.51 

36.16 

29.97 

36.72 

30.47 

37  32 

69.7 

35  41 

29.33 

35.69 

29.57 

36  23 

30.04 

36.79 

30.54 

37.40 

69.8 

35.49 

29.39 

35.76 

29.64 

36.31 

30.11 

36.87 

30.61 

37.48 

69.9 

35  56 

29.46 

35  83 

29.70 

36.39 

30.17 

36.96 

30.67 

37.56 

70.0 

35  64 

29.52 

35.91 

29.76 

36.46 

30.24 

37  02 

30.74 

37.64 

70.1 

35  71 

29.59 

35  98 

29.82 

36  54 

30.31 

37  10 

30.81 

37.72 

70.2 

35.78 

29.65 

36  05 

29.89 

36  61 

30.38 

37.19 

30.88 

37.80 

70.3 

35.86 

29.72 

36  13 

29.95 

36  69 

30.44 

37  27 

30.95 

37.89 

70.4 

35.93 

29.78 

36.20 

30.01 

36.76 

30.51 

37  36 

31.01 

37.97 

70.5 

36  01 

29.85 

36.28 

30.08 

36.84 

30.58 

37.43 

31.09 

38  06 

70.6 

36.08 

29.91 

36  35 

30.15 

36.92 

30.64 

37.61 

31.16 

38.13 

70.7 

36  16 

29.97 

36  43 

30.21 

36  99 

30.71 

37  59 

31.23 

38.22 

70.8 

36  23 

30.04 

36  50 

30.28 

37  07 

30.78 

37.67 

31.30 

38  30 

70.9 

36  31 

30.11 

36.58 

30.35 

37.15 

30.85 

37  76 

31.37 

38  38 

71.0 

36  38 

30.17 

36  65 

30.41 

37  23 

30.91 

37.83 

SI.  44 

38.47 

71.1 

36  46 

30.24 

36.73 

30.48 

37.31 

30.98 

37  91 

31.51 

38  66 

71.2 

36  53 

30.30 

36.80 

30.55 

37.39 

31.05 

37.99 

31.59 

38  63 

71.3 

36  60 

30.37 

36.88 

30.61 

37.47 

31.12 

38  07 

31.66 

38.72 

71.4 

36.68 

30.44 

36.95 

30.68 

37.55 

31.19 

38.16 

31.73 

38  80 

71.5 

36  75 

30.50 

37  03 

30.75 

37.63 

31.26 

38  24 

31.80 

38.88 

71.6 

36  83 

30.57 

37.11 

30.81 

37.71 

31.33 

38  32 

31.87 

38.97 

71.7 

36.90 

30.64 

37.19 

30.88 

37.79 

31.40 

38  40 

31.94 

39  05 

71.8 

36.98 

30.70 

37.27 

30.95 

37.87 

31.47 

38  49 

32.01 

39.14 

71.9 

37.05 

30.77 

37  34 

31.01 

37.94 

31.54 

38  57 

32.09 

39  23 

72.0 

37.13 

30.84 

37.42 

31.08 

38.02 

31.61 

38  66 

32.17 

39.31 

72.1 

37  21 

30.90 

37  50 

31.15 

38.11 

31. 6S 

38.74 

32.24 

39.40 

72.2 

37  29 

30.97 

37.58 

31.22 

38.19 

31.75 

38.82 

32.32 

39.49 

72.3 

37  36 

31.03 

37.66 

31.29 

38  27 

31.82 

38.90 

32.39 

39  67 

72.4 

37  44 

31.10 

37  73 

31.36 

38  35 

31.89 

38.98 

32.47 

39.66 

72.5 

37.52 

31.17 

37.81 

31.42 

38.43 

31.96 

39  07 

32.54 

39.76 

72.6 

37  60 

31.24 

37.89 

31.49 

38.51 

32.04 

39  16 

32.62 

39.83 

72.7 

37.67 

31.31 

37  97 

31.56 

38  59 

32.11 

39.24 

32.69 

39.92 

72.8 

37.75 

31.37 

38  05 

31.63 

38  67 

52.18 

39  33 

32.77 

40.01 

72.9 

37  83 

31.44 

38  13 

31 .  70 

38.76 

32.26 

39  41 

32.84 

40.10 

XVI] 


231 


Table- 

-Continued. 

6 

21°  C. 

22° 

C. 

23° 

C. 

24° 

c. 

25° 

c. 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

SCALE 
READING 

by 

by 

by 

by 

by 

by 

by 

by 

by 

weiffht 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

29 .  89 

36  63 

30.40 

37  23 

30.91 

37  86 

SI.  47 

38  53 

32.05 

68.0 

29  ,9-5 

36  71 

30.47 

37  31 

30.99 

37  95 

31.54 

38.61 

32.13 

68.1 

SO  02 

36  79 

30.54 

37  39 

31.06 

38  03 

31.62 

38  70 

32.21 

68.2 

SO.  09 

36  87 

30.61 

37  48 

31.13 

38.12 

31.69 

38  79 

32.29 

68.3 

SO. 16 

36  96 

30.68 

37.56 

31.21 

38  21 

31.77 

38.88 

82.87 

68.4 

SO.  2^ 

37  03 

30.75 

37  65 

31.28 

38  30 

31.84 

38.96 

32.45 

68.5 

SO .  HO 

37  12 

30.82 

37  73 

31.35 

38  38 

31.92 

39  06 

32.53 

68.6 

SO.  37 

37  20 

30.89 

37  82 

31.43 

38  47 

31.99 

39  15 

32.61 

68.7 

SO  43 

37  28 

30.96 

37  90 

31.50 

38  56 

32.07 

39.24 

82.69 

68.8 

SO.  50 

37  36 

81.  OS 

37  98 

31.57 

38.64 

32.15 

39  33 

82.77 

68.9 

SO  57 

37  45 

SI.  10 

38  07 

31.65 

38  73 

32.23 

39  43 

82.86 

69.0 

SO. 6  ft 

37  53 

31.17 

38.15 

31.72 

38  82 

32.31 

39  52 

32.94 

SO. 71 

37  61 

31.25 

38  24 

31.79 

38  90 

32.39 

39  61 

38.02 

69^2 

SO.  78 

37  69 

31.32 

38  32 

31.87 

38  99 

32.47 

39  70 

33.10 

69.3 

SO.  85 

37.78 

31.39 

38.41 

31.94 

39  08 

32.55 

39.80 

83.18 

69.4 

SO.  92 

37  86 

31.46 

38  50 

32.02 

39  17 

82.63 

39  89 

33.26 

69.5 

SO .  99 

37  94 

31.54 

38  58 

32.09 

39  26 

82.71 

39  98 

33.34 

69.6 

SI  .06 

38  03 

31.61 

38  67 

32.17 

39  35 

82.78 

40.07 

33.43 

69.7 

SI  IS 

38.11 

31.68 

38  75 

32.25 

39.46 

82.86 

40.17 

88.51 

69.8 

SI.  20 

38  19 

31.75 

38.84 

32.33 

39.64 

82.95 

40.26 

88.59 

69.9 

SI.  27 

38  28 

31.83 

38.92 

32.41 

39  63 

88.02 

40  35 

83.67 

70.0 

SI. 35 

38  36 

31.90 

39  01 

32.49 

39  72 

88.11 

40  44 

83.75 

70.1 

SI.  42 

38  45 

31.97 

39  10 

32.57 

39  81 

88.19 

40  53 

38.84 

70.2 

SI.  49 

38  53 

32.05 

39  19 

32.65 

39  90 

33.27 

40  62 

88.92 

70.3 

SI.  56 

38  61 

32.12 

39  28 

32.72 

39.99 

38.85 

40.72 

34.00 

70.4 

SI. 63 

38  70 

32.20 

39  37 

32.80 

40  08 

83.43 

40.81 

84.08 

70.5 

SI. 70 

38  78 

32.28 

39.46 

32.88 

40.17 

S8.51 

40  90 

84.17 

70.6 

SI. 78 

38  87 

32.36 

39  55 

32.96 

40.26 

33.59 

40.99 

84.25 

70.7 

SI.  85 

38  95 

32.43 

39.64 

33.04 

40  35 

38.68 

41  08 

34.83 

70.8 

SI.  92 

39  04 

32.51 

39  73 

33.12 

40.45 

33.76 

41.18 

84. 4^ 

70.9 

SI.  99 

39  12 

32.59 

39  82 

33.20 

40.54 

33.84 

41.27 

84.50 

71.0 

S2.07 

39  21 

32.67 

39.91 

33.28 

40  63 

33.92 

41  36 

84.58 

71.1 

S2.15 

39  30 

32.74 

40.00 

33.36 

40  72 

34.00 

41.46 

34.67 

71.2 

S2.22 

39  39 

32.82 

40.09 

33.44 

40  81 

34.08 

41.55 

34.75 

71.3 

S2.S0 

39  48 

32.90 

40.18 

33.52 

40.90 

84.17 

41.64 

34.83 

71.4 

S2.37 

39  57 

32.98 

40.27 

33.60 

40  99 

84.25 

41.74 

34.92 

71.5 

S2.45 

39  65 

33.05 

40  36 

33.68 

41  08 

84.88 

41.83 

35.00 

71.6 

S2.53 

39  74 

33.13 

40  45 

33.76 

41.18 

34-41 

41  93 

35.08 

71.7 

S2.60 

39  83 

33.21 

40.54 

33.84 

41.27 

34.50 

42  02 

85.17 

71.8 

S2.68 

39  92 

33.29 

40.63 

33.92 

41  36 

84.68 

42  11 

35.85 

71.9 

S2.76 

40.01 

33.37 

40.72 

34.00 

41.45 

34.66 

42.21 

35.84 

72.0 

S2.83 

40.10 

33.45 

40  81 

34.08 

41  55 

34.74 

42  30 

85.42 

72.1 

S2.91 

40  18 

33.52 

40  90 

34.16 

41  64 

34.88 

42.40 

35.51 

72.2 

S2.98 

40  27 

33.60 

40.99 

34.24 

41  73 

84.91 

42.49 

85.59 

72.3 

SS.06 

40  36 

33.68 

41  08 

34.33 

41  82 

84.99 

42.58 

85.68 

72.4 

SS.14 

40  45 

33.76 

41.17 

34.41 

41  92 

85.08 

42  68 

85.76 

72.5 

SS.22 

40  54 

33.84 

41.26 

3449 

42.01 

35.16 

42.77 

35.85 

72.6 

SS.29 

40  62 

33.91 

41.35 

34.57 

42.10 

85.24 

42  87 

35.93 

72.7 

SS.S7 

40.71 

33.99 

41.45 

34.65 

42.19 

35.83 

42.96 

36.02 

72.8 

SS.45 

40  80 

34.07 

41.54 

34.73 

42  29 

85.41 

43.06 

36.10 

72.9 

232 
6 


METHODS   OF   ANALYSIS 


[Chap. 


Table  17.— Alcohoi; 


17.5 

°C. 

18° 

C. 

19° 

c. 

20° 

C. 

21-c.  : 

SCALE 
READING 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent* 

by 

by 

by 

by 

by 

by 

by 

by 

by 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

73.0 

37  91 

31.51 

38  21 

31.77 

38.84 

32.33 

39.50 

32.92 

40.18 

73.1 

37.98 

31.58 

38  29 

31.84 

38  92 

32.40 

39  59 

32.99 

40.27 

73.2 

38  06 

31.65 

38  37 

31.90 

39  00 

32.48 

39.67 

33.07 

40.36 

73.3 

38.14 

31.71 

38  45 

31.97 

39  08 

32.55 

39  76 

33.15 

40.44 

73.4 

38  22 

31.78 

38  53 

32.04 

39.17 

32.62 

39.84 

33.22 

40.53 

73.5 

38  30 

31.85 

38  61 

32.12 

39  25 

32.70 

39  93 

33.30 

40.62 

73.6 

38  38 

31.92 

38  69 

32.19 

39.34 

32.77 

40.02 

33.37 

40.70 

73.7 

38.46 

31.99 

38  77 

32.26 

39  42 

32.85 

40.10 

33.45 

40.79 

73.8 

38.64 

32.06 

38  85 

32.34 

39  50 

32.92 

40.19 

33.53 

40.88 

73.9 

38.62 

32.13 

38  93 

32.41 

39  59 

32.99 

40.28 

33.60 

40.97 

74.0 

38  70 

32.20 

39  01 

32.48 

39  67 

33.07 

40.36 

33.68 

41.05 

74.1 

38  78 

32.27 

39  09 

32.55 

39  76 

33.15 

40.45 

33.76 

41.14 

74.2 

38  86 

32.35 

39.18 

32.63 

39.84 

33.22 

40.53 

33.83 

41.23 

74.3 

38  94 

32.42 

39  26 

32.70 

39  92 

33.30 

40.62 

33.91 

41  32 

74.4 

39  02 

32.^9 

39  34 

32.77 

40  01 

33.37 

40.71 

33.98 

41.41 

74.5 

39.10 

32.56 

39  43 

32.85 

40  09 

33.45 

40.79 

34.06 

41  50 

74.6 

39  18 

32.63 

39  51 

32.92 

40  18 

33.53 

40.88 

34.14 

41.59 

74.7 

39  26 

32.70 

39.59 

32.99 

40.27 

33.60 

40.97 

34.22 

41.68 

74.8 

39  36 

32.78 

39.68 

33.07 

40  35 

33.68 

41.06 

34.30 

41.77 

74.9 

39  43 

32.85 

39.76 

33.15 

40.44 

33.76 

41.14 

34.38 

41.86 

75.0 

39  51 

32.92 

39  84 

33.22 

40  53 

33.83 

41  23 

34.46 

41  96 

75.1 

39.60 

32.99 

39  93 

33.30 

40.61 

33.91 

41.32 

34.54 

42  04 

75.2 

39  68 

33.07 

40  01 

33.37 

40  70 

33.98 

41.41 

34. 61 

42.13 

75.3 

39  76 

33.15 

40  09 

33.45 

40.78 

34.06 

41.60 

34.69 

42.22 

75.4 

39  84 

33.22 

40  18 

33.53 

40.87 

34.14 

41.58 

34.77 

42.31 

75.5 

39.93 

33.30 

40  27 

33.60 

40.96 

34.22 

41.67 

34.85 

42.40 

75.6 

40.01 

33.37 

40  35 

33.68 

41.04 

34.30 

41.76 

34.93 

42.49 

75.7 

40  09 

33.45 

40  44 

33.76 

41  13 

34.38 

41  86 

35.01 

42.68 

75.8 

40  18 

33.53 

40  53 

33.83 

41  22 

34.45 

41.94 

35.09 

42.67 

75.9 

40.27 

33.60 

40  61 

33.91 

41.31 

34.53 

42  03 

35.17 

42.76 

76.0 

40  35 

33.68 

40  70 

33.98 

41.40 

34. 61 

42.12 

35.25 

42.85 

76.1 

40.44 

33.76 

40.78 

34. 06 

41.48 

34.68 

42.21 

35.33 

42.96 

76.2 

40.53 

33.83 

40  87 

34.14 

41.57 

34.77 

42.30 

35.41 

43.04 

76.3 

40.61 

33.91 

40.96 

34.22 

41.66 

34.84 

42.39 

35.50 

43.13 

76.4 

40.70 

33.98 

41  04 

34.29 

41.75 

34.92 

42.48 

35.58 

43.22 

76.5 

40  78 

34.06 

41  13 

34.37 

41.83 

35.00 

42.57 

35.66 

43.32 

76.6 

40.87 

34.14 

41.22 

34.45 

41.92 

35.08 

42  66 

35.74 

43.41 

76.7 

40.96 

34.22 

41.30 

34.53 

42.01 

35.16 

42.75 

35.82 

43.60 

76.8 

41.04 

34.29 

41.39 

34. 60 

42.10 

35.24 

42.84 

35.90 

43.60 

76.9 

41.13 

34.37 

41.48 

34.68 

42.19 

35.32 

42.93 

35.98 

43.69 

77.0 

41.22 

34.45 

41. or? 

34.76 

42.28 

35.40 

43.02 

36.07 

43.79 

77.1 

41.31 

34.52 

41.65 

34.84 

42.37 

35.48 

43.11 

36.15 

43.88 

77.2 

41.39 

34. 60 

41.74 

34.91 

42.46 

35.56 

43.20 

36.24 

43.97 

77.3 

41.48 

34.68 

41.83 

34.99 

42.54 

35.64 

43  30 

86.32 

44.07 

77.4 

41.57 

34.75 

41.91 

35.07 

42.63 

35.72 

43.39 

36.40 

44.16 

77.5 

41.66 

34.83 

42.00 

35.15 

42.72 

35.80 

43.48 

36.49 

44.26 

77.6 

41.75 

34.91 

42.09 

35.23 

42.81 

35.88 

43.57 

36.57 

44.36 

77.7 

41.83 

34.98 

42.17 

35.30 

42,90 

35.96 

43.67 

36.66 

44.46 

77.8 

41.92 

35.06 

42.26 

35.38 

42.99 

36.04 

43.76 

36.74 

44.54 

77.9 

42.01 

35.14 

42.35 

35.46 

43.08 

36.13 

43.85 

36.82 

44.64 

XVI] 


Table.— Continued. 


WINES 


233 
6 


21»C. 

22 

C. 

23 

c. 

24 

c. 

25 

c. 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

SCALE 
READING 

by 

by 

by 

by 

by 

by 

by 

by 

by 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

volume 

weight 

SS.52 

40  88 

34-15 

41  63 

34.81 

42  38 

35.49 

43.16 

36.18 

73.0 

S3. 60 

40.97 

34.2s 

41.72 

34.89 

42.47 

35.58 

43  24 

36.27 

73.1 

SS.68 

41  06 

34.31 

41.81 

34.98 

42.56 

35.66 

43  33 

36.35 

73.2 

SS.75 

41.16 

34.S9 

41.90 

35.06 

42  66 

35.74 

43  43 

36.43 

73.3 

SS.8S 

41.24 

34.47 

41  99 

35.14 

42.75 

35.88 

43  52 

36.52 

73.4 

SS.91 

41  33 

34.55 

42.08 

35.22 

42.84 

35.91 

43  61 

36.60 

73.5 

SS.98 

41  42 

34.63 

42.17 

35.31 

42  93 

35.99 

43.70 

36.68 

73.6 

S4.06 

41.51 

S4.71 

42.27 

35.39 

43.03 

36.08 

43  80 

36.77 

73.7 

S4-U 

41.60 

34.79 

42.36 

35.47 

43  12 

36.16 

43  89 

36.85 

73.8 

34.22 

41.69 

34.87 

42  46 

35.55 

43  21 

36.24 

43  98 

36.93 

73.9 

34.30 

41  78 

34.95 

42.54 

35.64 

43  31 

36.33 

44  08 

37.02 

74.0 

34.38 

41  87 

35. OS 

42  63 

35.72 

43  40 

36. 41 

44  18 

37.11 

74.1 

34.46 

41  96 

35.12 

42.72 

35.80 

43  49 

36.49 

44.28 

37.20 

74.2 

34.54 

42  06 

35.20 

42.82 

35.88 

43  68 

36.58 

44  38 

87.29 

74.3 

34.62 

42  15 

35.28 

42.91 

35.97 

43  68 

36.66 

44,48 

37.38 

74.4 

34.70 

42.24 

35.36 

43.00 

36.05 

43  77 

36.74 

44.57 

37.47 

74.5 

34.78 

42  33 

35.45 

43.09 

36.13 

43.86 

36.83 

44.67 

37.56 

74.6 

34.86 

42.42 

35.53 

43  19 

36.22 

43.96 

36.91 

44.77 

37.65 

74.7 

34.94 

42.51 

35.61 

43.28 

36.30 

44.05 

36.99 

44.87 

37.75 

74.8 

35.02 

42.61 

35.69 

43  37 

36. S9 

44.15 

37.08 

44  97 

37.84 

74.9 

35.10 

42.70 

35.78 

43.46 

36.47 

44.26 

37.17 

45.07 

37.93 

75.0 

35.18 

42.79 

35.86 

43.56 

36.55 

44.34 

37.26 

45  18 

38.02 

75.1 

35.26 

42.88 

35.95 

43  65 

36.64 

44.44 

37.35 

45  29 

38.12 

75.2 

35.34 

42  97 

36.03 

43.74 

36.72 

44.63 

37.44 

46  39 

38.21 

75.3 

35.4s 

43.07 

36.11 

43.83 

36.81 

44.63 

37.63 

46.50 

38.31 

75.4 

35.51 

43.16 

36.20 

43.92 

36.89 

44.73 

37.62 

45.61 

38.40 

75.5 

35.59 

43.25 

36.28 

44.02 

36.97 

44.83 

37.71 

45.71 

38.50 

75.6 

35.67 

43  35 

36.36 

44.12 

37.06 

44.93 

37.80 

46.82 

38.60 

75.7 

35.75 

43.44 

36. 45 

44.21 

37.15 

46  03 

37.89 

46  92 

38.69 

75.8 

35.84 

43  53 

36.53 

44  31 

37.24 

45  13 

37.98 

46  02 

38.79 

75.9 

35.92 

43.63 

36.62 

44.41 

37.33 

45.24 

38.08 

46  12 

38.88 

76.0 

36.00 

43.72 

36.70 

44.60 

37.42 

45.34 

38.17 

46  23 

38.98 

76.1 

36.08 

43.81 

36.79 

44.60 

37.50 

45.44 

38.27 

46.34 

39.08 

76.2 

86.17 

43.91 

36.87 

44.70 

37.59 

45  66 

38.36 

46.45 

39.18 

76.3 

S6.25 

44.00 

36.96 

44.80 

57.68 

45.65 

38.46 

46  56 

39.29 

76.4 

S6.34 

44.10 

37.04 

44.89 

37.77 

45.76 

38.55 

46  67 

89.89 

76.5 

S6.42 

44.19 

37.13 

44.99 

37.86 

46  86 

38.65 

46.78 

39.49 

76.6 

S6.51 

44.29 

37.22 

45.09 

37.95 

45.96 

38.74 

46.89 

39.59 

76.7 

36.59 

44.38 

37.30 

46.19 

38.04 

46.07 

38.84 

47.00 

39.69 

76.8 

S6.68 

44.48 

37.39 

46  30 

38.13 

46.18 

38.93 

47.11 

39.80 

76.9 

S6.76 

44.57 

37.47 

45  40 

38.23 

46  29 

39.03 

47.23 

39.90 

77.0 

36.85 

44.67 

37.56 

46.50 

38.32 

46.40 

39.13 

47.34 

40.00 

77.1 

36.93 

44.76 

37.65 

45.60 

38. 42 

46.51 

39.23 

47  45 

40.11 

77.2 

37.02 

44.86 

37.73 

45.70 

38.51 

46.62 

39.34 

47.57 

40.22 

77.3 

37.10 

44.95 

37.82 

45.81 

38.60 

46.73 

39.44 

47.68 

40.32 

77.4 

37.19 

45.05 

37.91 

45.91 

38.70 

46  84 

39.54 

47.80 

40.43 

77.5 

37.28 

45.15 

37.99 

46.01 

38.79 

46  95 

39.64 

47.91 

40.54 

77.6 

37.  S6 

45.25 

38.08 

46.12 

38.89 

47.06 

39.74 

48.02 

40.65 

77.7 

37.45 

45.35 

38.18 

46.23 

38.98 

47.17 

39.85 

48.14 

40.75 

77.8 

S7.5S 

45.45 

38.27 

46.34 

39.08 

47.28 

39.95 

48.26 

40.86 

77.9 

234 
6 


METHODS    OF   ANALYSIS 


[Chap. 


Table  17.— Alcohoi 


17.5 

°c. 

18 

C. 

19° 

C. 

20° 

c. 

21°  C. 

READING 

Per  cent 

by 
volume 

Per  cent 

by 
weight 

Per  cent 

by 
volume 

Per  cent 
weight 

Per  cent 

by 
volume 

Per  cent 

by 
weight 

Per  cent 

by 
volume 

Per  cent 

by 
weight 

Per  cent 

by 
volume 

78.0 
78.1 
78.2 
78.3 

78.4 

42.09 
42.18 
42.26 
42  36 
42.44 

S5.22 
35.30 
35.38 
35.45 
35.53 

42.43 
42  52 
42  61 
42.70 
42,78 

35.54 
35.62 
35.70 
35.77 
35.85 

43  17 
43.27 
43.36 
43  45 
43.54 

36.21 
36.29 
36.38 
36.46 
36.54 

43.94 
44.04 
44.13 
44.23 
44,32 

36.91 
36.99 
37.08 
37.16 
37.25 

44.73 
44.83 
44.92 
46.02 
45.12 

78.5 
78.6 
78.7 
78.8 
78.9 

42.52 
42.61 
42.69 
42.78 
42.86 

35.61 
35.69 
35.77 
35.84 
35.92 

42.87 
42.96 
43.05 
43.14 
43  23 

35.93 
36.01 
36.09 
36.17 
36.26 

43.63 
43.72 
43.82 
43  91 
44,00 

36.63 
36.71 
36.79 
36.88 
36.96 

44,42 
44,51 
44.60 
44.70 
44.79 

37.33 
37.42 
37.50 
37.59 
37.68 

46.22 
46  32 
46.42 
46  62 
45.62 

79.0 
79.1 
79.2 
79.3 

79.4 

42.95 
43.04 
43  13 
43.22 
43.31 

36.00 
36.08 
36.16 
36.25 
36.33 

43.32 
43.41 
43  50 
43  59 
43  68 

36.34 
36.42 
36.50 
36.59 
36.67 

44.09 
44.19 
44.28 
44.38 
44.47 

37.04 
37.13 
37.21 
37.30 
37.38 

44.89 
44.98 
45.08 
45.18 
45.28 

37.76 
37.85 
37.94 
38.02 
38.11 

46.72 
46.82 
45.92 
46.02 
46.13 

79.5 
79.6 

79.7 
79.8 
79.9 

43.40 
43.49 
43.58 
43.67 
43.76 

36.41 
36.49 
36.57 
36.66 
36.74 

43.77 
43  86 
43.95 
44.06 
44.14 

36.75 
36.83 
36.92 
37.00 
37.09 

44.56 
44.65 
44.75 
44.84 
44,93 

37.47 
37.56 
37.64 
37.73 
37.81 

45.38 
45.48 
45  58 
46,68 
46,78 

38.20 
38.30 
38.39 
38.48 
38.57 

46.24 
46.34 
46.46 
46.56 
46.67 

80.0 

43.85 

36.82 

44.24 

37.17 

45.04 

37.90 

45.88 

38.67 

46.77 

XVIJ 


Table— Concluded . 


WINES 


235 
6 


21°  C. 

22°  C. 

23°  C. 

24°  C. 

25°  C. 

Per  cent 

by 
weight 

Per  cent 

by 
volume 

Per  cent 

by 
weight 

Per  cent 

by 
volume 

Per  cent 
by 

weight 

Per  cent 

by 
volume 

Per  cent 

by 
weight 

Per  cent 

by 
volume 

Per  cent 

by 
weight 

SCALE 
READING 

S7.62 
S7.71 
S7.79 
57.88 
S7.97 

S8.06 
S8.15 
S8.24 
S8.33 
S8.43 

S8.52 
S8.61 
S8.70 
S8.80 
S8.89 

S8.98 
'   59.08 
\   S9.18 

S9.28 
1   59.38 

59.48 

i 

45.56      38.37 
45.66      38.46 
45.76      38.56 
45.86      38.65 
46.96      38.75 

46.07      38.84 
46.17      38.93 
46.28      39.03 
46.39      39.13 

46.60  39.23 

46.61  39.33 
46.72      39.43 
46.83      39.54 
46,93      39.64 
47.04      39.74 

47.15      39.84 
47.26      39.94 
47.37      40.04 
47.48      40.14 
47.59      40.:?4 

47.70      40.35 

46.45      39.18 
46.56      39.29 
46.67      39.39 

46.78  39.49 

46.89  39.59 

47.00  39.69 

47.11  39.80 

47.22  39.90 
47.34      40.00 

47.45  40.// 

47.56  40.21 

47.67  40.S;2 

47.79  40.4^ 

47.90  40-53 

48.01  40.63 

48.12  40.74 

48.23  40.84 
48.34      40.95 

48.46  41-05 

48.57  4/./6 

48.68  41-26 

47.40      40-05 
47.61      40.16 
47.63      40.27 
47.74      40.37 
47.85      40-48 

47.97      40.59 
48.08      40.69 
48.19      40.80 
48.31      40.90 
48.42      41.01 

48.63      4/./^ 
48.65      4/-?^ 
48.76      41 -S3 
48.88      4/. 44 
48.99      41 -H 

49.10      4/. 65 
49.22      4/. 76 
49.33      41.86 
49.45      4^97 
49.56      42.08 

49.68      ig./S 

48.37       40.97 
48.49      41-08 
48.60      41-18 
48.72      4/. ^9 
48.84      41-40 

48.96      4/. 5/ 
49,07      41-62 
49,19      4/73 
49.31      4/84 
49.42      41-95 

49.64      4:^.05 
49.66      42.16 
49.77      4:?.:87 
49,89      4:2.38 
60,01      42.49 

50.13       4;g.60 
50.24      4^.7/ 
60.36      42.82 
50.48      43.93 
60.69      43.04 

50.71      43/5 

78.0 

78.1 
78.2 
78.3 
78.4 

78.5 
78.6 
78.7 
78.8 
78.9 

79.0 
79.1 
79.2 
79.3 
79.4 

79.5 
79.6 
79.7 
79.8 
79.9 

80.0 

1 

! 
i 

• 

236  METHODS    OF   ANALYSIS  [Chap. 

GLYCEROL  IN  DRY  WINES. 

7  Method  I.     (By  Direct  Weighing) — Tentative. 

Evaporate  100  cc.  of  the  wine  in  a  porcelain  dish  on  a  water  bath  to  a  volume 
of  about  10  cc.  and  treat  the  residue  with  about  5  grams  of  fine  sand  and  4-5  cc.  of 
milk  of  lime  (containing  about  15%  of  calcium  oxid)  for  each  gram  of  extract  pres- 
ent and  evaporate  almost  to  dryness.  Treat  the  moist  residue  with  50  cc.  of  90% 
alcohol  by  volume,  remove  the  substance  adhering  to  the  sides  of  the  dish  with  a 
spatula  and  rub  the  whole  mass  to  a  paste.  Heat  the  mixture  on  a  water  bath, 
with  constant  stirring,  to  incipient  boihng  and  decant  the  Uquid  through  a  filter 
into  a  small  flask.  Wash  the  residue  repeatedly  by  decantation  with  10  cc.  portions 
of  hot  90%  alcohol  until  the  filtrate  amounts  to  about  150  cc.  Evaporate  the  filtrate 
to  a  sirupy  consistency  in  a  porcelain  dish  on  a  hot,  but  not  boiling,  water  bath; 
transfer  the  residue  to  a  small,  glass-stoppered,  graduated  cylinder  with  20  cc.  of 
absolute  alcohol  and  add  3  portions  of  10  cc.  each  of  anhydrous  ether,  shaking 
thoroughly  after  each  addition.  Let  stand  until  clear,  then  pour  off  through  a 
filter,  and  wash  the  cylinder  and  filter  with  a  mixture  of  1  part  of  absolute  alcohol 
to  1|  parts  of  anhydrous  ether,  also  pouring  the  wash  liquor  through  the  filter. 
Evaporate  the  filtrate  to  a  sirupy  consistency,  dry  for  an  hour  at  the  temperature 
of  boiling  water,  weigh,  ignite  and  weigh  again.  The  loss  on  ignition  gives  the 
weight  of  glycerol. 

8  Method  II.  (By  Oxidation  with  Bichromate) — Tentative. 

Evaporate  100  cc.  of  the  wine  in  a  porcelain  dish  on  a  water  bath,  the  temperature 
of  which  is  maintained  at  85°-90°C.,  to  a  volume  of  10  cc.  and  treat  the  residue  with 
about  5  grams  of  fine  sand  and  5  cc.  of  milk  of  lime  (containing  the  equivalent  of 
15  grams  of  calcium  oxid).  Proceed  from  this  point  as  directed  under  XIX,  6,  be- 
ginning with  the  clause  "evaporate  almost  to  dryness,  with  frequent  stirring". 
Observe  the  precautions  given  concerning  the  temperature  at  which  all  evapora- 
tions are  to  be  made. 

9  GLYCEROL  IN   SWEET  WINES.— TENTATIVE. 

With  wines  whose  extract  exceeds  5  grams  per  100  cc,  heat  100  cc.  to  boiling  in 
a  flask  and  treat  with  successive  small  portions  of  milk  of  lime  until  the  wine  be- 
comes first  darker  and  then  lighter  in  color.  Cool,  add  200  cc.  of  95%  alcohol  by 
volume,  allow  the  precipitate  to  subside,  filter  and  wash  with  95%  alcohol.  Treat 
the  combined  filtrate  and  washings  as  directed  in  7  or  8. 

10  GLYCEROL-ALCOHOL  RATIO.— TENTATIVE. 

Express  this  ratio  as  x  :  100,  in  which  x  is  obtained  by  multiplying  the  percentage 
by  weight  of  glycerol  by  100  and  dividing  the  result  by  the  percentage  of  alcohol 
by  weight. 

EXTRACT. 

11  From  the  Specific  Gravity  of  the  Dealcoholized  Wine.— Tentatife. 

Calculate  the  specific  gravity  of  the  dealcoholized  wine  by  the  following  formula: 

S  =  G-1-1  —  Ain  which 

S  =  specific  gravity  of  the  dealcoholized  wine; 
G  =  specific  gravity  of  the  wine,  3;  and 

A  =  specific  gravity  of  the  distillate  obtained  in  the  determination  of  alco- 
hol, 4  (a). 


XVI]  WINES  237 

From  IX,  9,  ascertain  the  per  cent  by  weight  of  extract  in  the  dealcoholized  wine 
corresponding  to  the  value  of  S.  Multiply  the  figure  thus  obtained  by  the  value  of 
S  to  obtain  the  grams  of  extract  per  100  cc.  of  wine. 

12  By  Evaporation.— Tentative. 

(a)  In  dry  wines,  having  an  extract  content  oj  less  than  3  grams  per  100  cc. — Evapo- 
rate 50  cc.  of  the  sample  on  a  water  bath  to  a  sirupy  consistency  in  a  75  cc.  flat- 
bottomed  platinum  dish,  approximately  85  mm.  in  diameter.  Heat  the  residue 
for  2^  hours  in  a  drying  oven  at  the  temperature  of  boiling  water,  cool  in  a  desicca- 
tor and  weigh  as  soon  as  the  dish  and  contents  reach  room  temperature. 

(b)  In  sweet  xvines. — When  the  extract  content  is  between  3  and  6  grams  per  100  cc, 
treat  25  cc.  of  the  sample  as  directed  under  (a). 

When  the  extract  exceeds  6  grams  per  100  cc,  however,  the  result,  obtained  as 
directed  under  11,  is  accepted  and  no  gravimetric  determination  is  attempted. 
This  is  because  of  the  serious  error  connected  with  drying  levulose  at  high  tempera- 
ture. 

13  NON-SUGAR  SOLIDS.— TENTATIVE. 

Determine  the  non-sugar  solids  (sugar-free  extract)  by  subtracting  the  amount 
of  reducing  sugars  before  inversion,  14,  from  the  extract,  11  or  12.  If  sucrose  is 
present  in  the  wine,  determine  the  non-sugar  solids  by  subtracting  the  sum  of  re- 
ducing sugars  before  inversion  and  the  sucrose  from  the  extract. 

14  REDUCING  SUGARS.-TENTATIVE. 

(a)  Dry  wines. — Place  200  cc.  of  the  wine  in  a  porcelain  dish,  exactly  neutralize 
with  N/1  sodium  hydroxid,  calculating  the  amount  required  from  the  determina- 
tion of  acidity,  25,  and  evaporate  to  about  one  fourth  the  original  volume.  Trans- 
fer to  a  200  cc.  flask,  add  sufficient  neutral  lead  acetate  solution  to  clarify,  dilute 
to  the  mark  with  water,  shake  and  filter  through  a  folded  filter.  Remove  the  lead 
with  dry  potassium  oxalate  and  determine  reducing  sugars  as  directed  under  VIII, 

25. 

(b)  Sweet  wines. — In  the  case  of  sweet  wines  approximate  the  sugar  content 
by  subtracting  2  from  the  result  in  the  determination  of  the  extract  and  employ 
such  a  quantity  of  the  sample  that  the  aliquot  taken  for  the  copper  reduction  shall 
not  exceed  245  mg.  of  invert  sugar.  Proceed  as  directed  in  (a)  except  that  this  smaller 
quantity  of  the  sample  is  taken  for  the  determination. 

SUCROSE. 

15  By  Reducing  Sugars  Before  and  After  Inversion. — Tentative. 

Proceed  as  directed  under  VIII,  18,  using  the  method  given  under  VlJI,  25,  for 

the  determination  of  reducing  sugars. 

16  By  Polarization. — Tentative. 

Polarize  part  of  the  filtrate,  obtained  in  14,  before  and  after  inversion  in 
a  200  mm.  tube  as  directed  under  VTII,  14  or  16.  In  calculating  the  percentage 
of  sucrose  the  relation  of  the  amount  of  sample  contained  in  100  cc.  to  the  normal 
weight  must  be  taken  into  consideration. 

17  COMMERCIAL   GLUCOSE.-TENTATIVE. 

Polarize  a  portion  of  the  filtrate,  obtained  in  14,  after  inversion  in  a  200 
mm.  jacketed  tube  at  87°C.   as  directed  "under  IX,    25.     In  calculating  the  per- 


238  METHODS    OF   ANALYSIS  [Chap. 

centage  of  glucose  the  relation  of  the  amount  of  sample  contained  in  100  cc.  to  the 
normal  weight  for  the  instrument  must  be  taken  into  consideration. 

18  ASH— TENTATIVE. 

Proceed  as  directed  under  VIII,  4,  employing  the  residue  from  50  cc.  of  the  wine. 

"19  ASH-EXTRACT  RATIO.— TENTATIVE. 

Express  results  as  1  :  x,  in  which  x  is  the  quotient  obtained  by  dividing  the 
grams  of  extract  per  100  cc.  by  the  grams  of  ash  per  100  cc. 

20  ALKALINITY  OF  THE  WATER-SOLUBLE  ASH.— TENTATIVE. 

Extract  the  ash,  obtained  as  directed  under  18,  with  successive  small  portions 
of  hot  water  until  the  filtrate  amounts  to  about  60  cc.  and  proceed  as  directed  under 
IX,  18.  Express  the  alkalinity  in  terms  of  the  number  of  cc.  of  N/10  acid  required 
to  neutralize  the  water-soluble  ash  from  100  cc.  of  the  wine. 

21  ALKALINITY  OF  THE  WATER-INSOLUBLE  ASH.— TENTATIVE. 

Ignite  the  filter  and  residue  from  20  in  the  platinum  dish  in  which  the  wine  was 
ashed,  and  proceed  as  directed  under  DC,  19.  Express  the  alkalinity  in  terms  of 
the  number  of  cc.  of  N/10  acid  required  to  neutralize  the  water-insoluble  ash  from 
100  cc.  of  the  wine. 

22  PHOSPHORIC  ACID.— TENTATIVE. 

Dissolve  the  ash,  obtained  as  directed  under  18,  in  50  cc.  of  boiling  nitric  acid 
(1  to  9),  filter,  wash  the  filter  and  determine  phosphoric  acid  in  the  combined  filtrate 
and  washings,  as  directed  in  I,  6  or  9.  If  the  ash  ignites  without  difficulty,  no  free 
phosphoric  acid  need  be  suspected.  Should  there  be  any  free  acid,  the  ash  remains 
black  even  after  repeated  leaching.  In  such  cases  calcimn  acetate  or  a  mixture 
containing  3  parts  of  sodium  carbonate  and  1  of  sodivun  nitrate  should  be  added 
to  avoid  loss  of  phosphoric  acid  before  attempting  to  ash. 

23  SULPHURIC  ACID.— TENTATIVE. 

Precipitate  directly  the  sulphuric  acid  in  50  cc.  of  the  wine  by  means  of  barium 
chlorid  solution,  after  acidifying  with  a  small  excess  of  hydrochloric  acid,  and  de- 
termine the  resulting  barium  sulphate  as  directed  under  II,  20.  Allow  the  precipi- 
tate to  stand  for  at  least  6  hours  before  filtering.     Report  as  sulphur  trioxid  (SOj). 

24  CHLORIN.-TENTATIVE. 

To  100  cc.  of  dry  wine  or  50  cc.  of  sweet  wine  add  sufficient  sodium  carbonate 
to  make  distinctly  alkaline.  Evaporate  to  dryness,  ignite  at  a  heat  not  above  low 
redness,  cool,  extract  the  residue  with  hot  water,  acidify  the  water  extract  with 
nitric  acid  and  determine  chlorin  as  directed  under  III,  15. 

25  TOTAL  ACIDS.— TENTATIVE. 

Measure  20  cc.  of  the  wine  into  a  250  cc.  beaker,  heat  rapidly  to  incipient  boiling 
and  immediately  titrate  with  N/10  sodium  hydroxid.  Determine  the  end  point  with 
neutral  0.05%  azolitmin  solution  as  an  outside  indicator.  Place  the  indicator  in 
the  cavities  of  a  spot  plate  and  spot  the  wine  into  the  azolitmin  solution.  The  end 
point  is  reached  when  the  color  of  the  indicator  remains  unchanged  by  the  addition 
of  a  few  drops  of  N/10  alkali  to  the  wine. 


XVI] 


239 


In  the  case  of  wines  which  are  artificially  colored  and  which  cannot  be  satis- 
factorily titrated  in  the  above  manner,  it  will  be  found  helpful  to  use  phenolphthalein 
powder  (1  part  of  phenolphthalein  mixed  with  100  parts  of  dry,  powdered  potassium 
sulphate)  as  an  indicator.  Place  this  indicator  in  the  cavities  of  a  spot  plate  and 
spot  the  wine  into  the  powder.  The  end  of  the  titration  is  indicated  when  the  pow- 
der acquires  a  pink  tint. 

Express  the  result  in  terms  of  tartaric  acid.  One  cc.  of  N/10  sodium  hydroxid 
is  equivalent  to  0.0075  gram  of  tartaric  acid. 

VOLATILE  ACIDS, 

26  Method  I.— Tentative. 

Heat  rapidly  to  incipient  boiling  50  cc.  of  the  wine  in  a  500  cc.  distillation  flask 
and  pass  steam  through  until  15  cc.  of  the  distillate  require  only  2  drops  of  N/10 
sodium  hydroxid  for  neutralization.  The  water  used  to  generate  the  steam  should 
be  boiled  several  minutes  before  connecting  the  steam  generator  with  the  distilla- 
tion flask  in  order  to  expel  carbon  dioxid.  Titrate  rapidly  with  N/10  sodium  hy- 
droxid, using  phenolphthalein  as  an  indicator.  The  color  should  remain  about  10 
seconds.  Express  the  result  as  acetic  acid.  One  cc.  of  N/10  sodium  hydroxid  is 
equivalent  to  0.0060  gram  of  acetic  acid. 


27 


Method  II.  (Hortvet  Method^)— Tentative. 


FIG.  8.    APPAR.\TUS  FOR  THE  DETERMIN.\TION  OF  VOLATILE  ACIDS. 


Introduce  10  cc.  of  the  wine,  previously  freed  from  carbon  dioxid,  into  the  inner 
tube  of  a  modified  Sellier  distillation  apparatus  (Fig.  8),  add  a  small  piece  of  paraf- 
fin to  prevent  foaming,  and  adjust  the  tube  and  its  contents  in  place  within  the  larger 
flask  containing  100  cc.  of  recently  boiled  water.  Connect  with  a  condenser  as  il- 
lustrated in  Fig.  8  and  distil  by  heating  the  outer  flask.  When  50  cc.  of  the  distillate 
have  been  collected,  emptj'  the  receiver  into  a  beaker  and  titrate  with  N/10  sodium 
hydroxid,  using  phenolphthalein  as  an  indicator.  Continue  the  distillation  and 
titrate  each  succeeding  10  cc.  of  distillate  until  not  more  than  1  drop  of  standard 
alkali  is  required  to  reach  the  neutral  point.  Usually  80  cc.  of  distillate  will  con- 
tain all  the  volatile  acid. 


240  METHODS    OF   ANALYSIS  [Chap. 

28  FIXED  ACIDS.-TENTATIVE. 

Multiply  the  amount  of  volatile  acids  by  1.25  and  subtract  this  from  the  total 
acids,  to  obtain  the  amount  of  fixed  acids,  expressed  as  tartaric  acid. 

29  TOTAL  TARTARIC  ACID'.— TENTATIVE. 

Neutralize  100  cc.  of  the  wine  with  N/1  sodium  hydroxid,  calculating  from  the 
acidity,  25,  the  number  of  cc.  of  N/1  alkali  necessary  for  the  neutralization.  If  the 
volume  of  the  solution  is  increased  more  than  10%  by  the  addition  of  the  alkali, 
evaporate  to  approximately  100  cc.  Add  to  the  neutralized  solution  0.075  gram 
of  tartaric  acid  for  each  cc.  of  N/1  alkali  added  and,  after  the  tartaric  acid  has  dis- 
solved, add  2  cc.  of  glacial  acetic  acid  and  15  grams  of  potassium  chlorid.  After 
the  potassium  chlorid  has  dissolved,  add  15  cc.  of  95%  alcohol  by  volume,  stir 
vigorously  until  the  potassium  bitartrate  starts  to  precipitate,  and  then  let  stand 
in  an  ice  box  for  at  least  15  hours.  Decant  the  liquid  from  the  separated  potassium 
bitartrate  on  a  Gooch,  prepared  with  a  very  thin  film  of  asbestos,  or  on  filter  paper 
in  a  Bijchner  funnel.  Wash  the  precipitate  and  filter  3  times  with  a  few  cc.  of  a 
mixture  of  15  grams  of  potassium  chlorid,  20  cc.  of  95%  alcohol  by  volume  and  100 
cc.  of  water,  using  not  more  than  20  cc.  of  the  wash  solution  in  all.  Transfer  the 
asbestos  or  paper  and  precipitate  to  the  beaker  in  which  the  precipitation  was 
made,  wash  out  the  Gooch  or  Buchner  funnel  with  hot  water,  using  about  50  cc.  in 
all,  heat  to  boiling  and  titrate  the  hot  solution  with  N/10  sodium  hydroxid,  using 
phenolphthalein  as  an  indicator.  Increase  the  number  of  cc.  of  N/10  alkali  re- 
quired by  1.5  cc.  to  allow  for  the  solubility  of  the  precipitate.  One  cc.  of  N/10  alkali 
is  equivalent,  under  these  conditions,  to  0.015  gram  of  tartaric  acid.  Subtract  the 
amount  of  tartaric  acid  added  from  this  result  to  obtain  the  grams  of  total  tartaric 
acid  per  100  cc.  of  the  wine. 

30  FREE  TARTARIC  ACID  AND  CREAM  OF  TARTAR^.— TENTATIVE. 

Calculate  the  free  tartaric  acid  and  cream  of  tartar  in  the  following  manner: 

Let  A  =  total  tartaric  acid  in  100  cc.  of  wine  divided  by  0.015; 
B  =  total  alkalinity  of  the  ash  (sum  of  C  and  D)  ; 
C  =  alkalinity  of  water-soluble  ash; 
D  =  alkalinity  of  water-insoluble  ash. 


Then 


31 


(1)  If  A  is  greater  than  B, 

Cream  of  tartar  =  0.0188  X  C;  and 
Free  tartaric  acid  =  0.015  X  (A-B). 

(2)  If  A  equals  B  or  is  smaller  than  B  but  greater  than  C, 

Cream  of  tartar  =  0.0188  X  C;  and 
Free  tartaric  acid  =  0. 

(3)  If  A  is  smaller  than  C, 

Cream  of  tartar  =  0.0188  X  A;  and 
Free  tartaric  acid  =  0. 

TANNIN  AND  COLORING  MATTER.-OFFICIAL. 

REAGENTS. 


(a)  N/10  oxalic  acid. — One  cc.  is  equivalent  to  0.004157  gram  of  tannin.      *'• 

(b)  Standard  potassium  permanganate  solution. — Dissolve  1.333  grams  of  potas- 
sium permanganate  in  1  liter  of  water  and  standardize  the  solution  against  (a). 


XVI]  WINES  241 

(C)  Indigo  solution. — Dissolve  6  grams  of  sodium  sulphindigotate  in  500  cc.  of 
water  by  heating;  cool,  add  50  cc.  of  concentrated  sulphuric  acid,  make  up  to  1 
liter  and  filter. 

(d)  Purified  honehlac¥\—Bo\\  100  grams  of  finely  powdered  boneblack  with  suc- 
cessive portions  of  hydrochloric  acid  (1  to  3),  filter  and  wash  with  boiling  water  until 
free  from  chlorin.    Keep  covered  with  water. 

32  DETERMINATION^. 

Dealcoholize  100  cc.  of  the  wine  by  evaporation  and  dilute  with  water  to  the 
original  volume.  Transfer  10  cc.  to  a  2  liter  porcelain  dish;  add  about  a  liter  of 
water  and  exactly  20  cc.  of  the  indigo  solution.  Add  the  standard  potassium 
permanganate  solution,  1  cc.  at  a  time,  until  the  blue  color  changes  to  green;  then  add 
a  few  drops  at  a  time  until  the  color  becomes  golden  yellow.  Designate  the  number 
of  cc.  of  permanganate  solution  used  as  "a". 

Treat  10  cc.  of  the  dealcoholized  wine,  prepared  as  above,  with  boneblack  for 
15  minutes;  filter  and  wash  the  boneblack  thoroughly  with  water.  Add  a  liter  of 
water  and  20  cc.  of  the  indigo  solution  and  titrate  with  permanganate  as  above. 
Designate  the  number  of  cc.  of  permanganate  used  as  "b". 

Then  a— b  =  c,  the  number  of  cc.  of  the  permanganate  solution  required  for  the 
oxidation  of  the  tannin  and  coloring  matter  in  10  cc.  of  the  wine. 

33  CRUDE  PROTEIN.-TENTATIVE. 

Determine  nitrogen  in  50  cc.  of  the  wine,  as  directed  under  I,  18,  21  or  23,  and 
multiply  the  result  by  6.25. 

34  PENTOSANS.-TENTATIVE. 

Proceed  as  directed  in  VIII,  64,  except  that  100  cc.  of  the  wine  and  43  cc.  of  hy- 
drochloric acid  (sp.  gr.  1.19)  are  used  in  beginning  the  distillation.  Owing  to  the 
interference  of  sugars  this  determination  can  be  made  in  dry  wines  only. 

35  GUM  AND   DEXTRIN.— TENTATIVE. 

Evaporate  100  cc.  of  the  wine  to  about  10  cc.  and  add  10  cc.  of  96%  alcohol  by 
volume.  If  gum  or  dextrin  be  present  (indicated  by  the  formation  of  a  voluminous 
precipitate),  continue  the  addition  of  alcohol,  slowly  and  with  stirring,  until  100 
cc.  have  been  added.  Let  stand  overnight,  filter,  and  wash  with  80%  alcohol  by 
volume.  Dissolve  the  precipitate  on  the  paper  with  hot  water,  hydrolyze  the 
filtrate  and  washings  with  hydrochloric  acid  and  proceed  as  directed  under  VIII,  60. 

36  NITRATES.— TENTATIVE. 

(a)  White  vxine. — Treat  a  few  drops  of  the  wine  in  a  porcelain  dish  with  2-3  cc. 
of  concentrated  sulphuric  acid,  which  contains  about  0.1  gram  of  diphenylamin* 
per  100  cc.  The  deep  blue  color  formed  in  the  presence  of  nitrates  appears  so  quickly 
that  it  is  not  obscured,  even  in  sweet  wine,  by  the  blackening  produced  by  the  ac- 
tion of  sulphuric  acid  on  the  sugar. 

(b)  Red  vxine. — Clarify  with  basic  lead  acetate,  filter,  remove  the  excess  of  lead 
from  the  filtrate  with  sodium  sulphate,  filter  again  and  treat  a  few  drops  of  this 
filtrate  as  directed  under  (a). 

37  COLORING  MATTERS.-TENTATIVE. 
Proceed  as  directed  under  XI. 


242  METHODS   OF   ANALYSIS 

38  PRESERVATIVES.-TENTATIVE. 

Proceed  as  directed  under  X. 

The  detection  of  added  boric  acid  is  somewhat  difficult  because  a  small  amount 
of  it  is  normally  present  in  certain  wines.  Therefore,  a  quantitative  determina- 
tion should  be  made.  The  determination  of  sulphurous  acid  must  also  be  quanti- 
tative. A  small  amount  of  salicylic  acid  is  also  normal  in  wine,  and  for  that  reason 
not  more  than  50  cc.  of  the  sample  should  be  used  in  testing  for  that  preservative. 

BIBLIOGRAPHY. 

'  U.  S.  Bur.  Standards  Bull.  9,  No.  3.     (Reprint  197). 

«  J.  Russ.  Phys.  Chem.  Soc,  1908,  40:  107. 

'  J.  Ind.  Eng.  Chem.,  1909,  1:  31. 

*  U.  S.  Bur.  Chem.  Bull.  162,  p.  72. 

"*  Ibid.,  p.  75. 

«  U.  S.  P.,  VIII,  1907,  p.  89. 

'  Ann.  Oenologie,  1871-72,  2:1. 

"Arch.  Hyg.,  1884,  2:  273. 


XVII.  DISTILLED  LIQUORS. 

1  SPECIFIC  GRAVXTY.-TENTATIVE. 

Determine  the  specific  gravity  at  -^  bj'  means  of  a  pycnometer  or  a  small, 
accurately  graduated  hydrometer. 

2  ALCOHOL  BY  WEIGHT.— OFFICIAL. 

Weigh  20-25  grams  of  the  sample  into  a  distillation  flask,  dilute  with  100  cc.  of 
water,  distil  nearly  100  cc.  and  weigh  the  distillate  or  make  to  volume  at  20°C.  and 
in  either  case,  determine  the  specific  gravity  as  directed  under  1 .  Obtain  the  corre- 
sponding percentage  of  alcohol  by  weight  from  XVI,  5,  multiply  this  figure  by  the 
weight  of  the  distillate,  and  divide  by  the  weight  of  the  sample  taken  to  obtain  the 
per  cent  of  alcohol  by  weight. 

The  alcohol  content  of  the  distillate  may  be  checked  by  determining  the  immer- 
sion refractometer  reading  and  obtaining,  from  XVI,  6,  the  percentage  of  alcohol. 

ALCOHOL  BY  VOLUME. 

3  Method  I.— Official. 

From  the  specific  gravity  of  the  distillate,  obtained  under  2,  ascertain  the  cor- 
responding percentage  of  alcohol  by  volume  from  XVI,  5.  Multiply  this  figure  by 
the  volume  of  distillate  and  divide  by  the  volume  of  the  sample  (calculated  from 
the  specific  gravity)  to  obtain  the  percentage  of  alcohol  by  volume  in  the  original 
sample. 

4  Method  II.— Tentative. 

Measure  25  cc.  of  the  sample  at  20°C.  into  a  distillation  flask,  dilute  with  100 
cc.  of  water,  distil  nearly  100  cc,  make  to  volume  at  20°C.  and  determine  the  spe- 
cific gravity  as  directed  in  1 .  Obtain,  from  XVI,  5,  the  corresponding  percentage 
of  alcohol  by  volume  in  the  distillate.  Multiply  by  4  to  obtain  the  percentage  of 
alcohol  by  volume  in  the  original  substance. 

The  alcohol  content  of  the  distillate  may  be  checked  by  determining  the  immer- 
sion refractometer  reading  and  obtaining  the  percentage  of  alcohol  from  XVI,  6. 

5  EXTRACT.— OFFICIAL. 

Weigh,  or  measure  at  20°C.,  100  cc.  of  the  sample,  evaporate  nearh'  to  dryness 
on  the  water  bath,  then  transfer  to  a  water  oven,  and  dry  at  the  temperature  of 
boiling  water  for  2^  hours. 

6  ASH.-OFFICLAL. 

Proceed  as  directed  under  VIII,  4,  employing  the  residue  from  the  determination 
of  the  extract,  5. 

7  ACIDITY.-TENTATIVE. 

Titrate  100  cc.  of  the  sample  (or  50  cc.  diluted  to  100  cc.  if  the  sample  is  dark) 
with  N/10  alkali,  using  phenolphthalein  as  an  indicator.  Express  the  result  as 
acetic  acid;  1  cc.  of  N/10  alkali  is  equivalent  to  0.0060  gram  of  acetic  acid. 

243 


244  METHODS    OF   ANALYSIS  [Chap. 

8  ESTERS.-TENTATIVE. 

Measure  200  cc.  of  the  sample  into  a  distillation  flask,  add  25  cc.  of  water  and 
distil  slowly  200  cc,  using  a  mercury  valve  to  prevent  loss  of  alcohol.  Exactly 
neutralize  the  free  acid  in  50  cc.  of  the  distillate  with  N/10  alkali,  add  a  measured 
excess  of  25-50  cc.  of  N/10  alkali,  and  either  boil  for  an  hour  under  a  reflux  con- 
denser, cool  and  titrate  with  N/10  acid,  or  allow  the  solution  to  stand  overnight 
in  a  stoppered  flask  with  the  excess  of  alkali,  heat  with  a  tube  condenser  for  30  min- 
utes at  a  temperature  below  the  boiling  point,  cool  and  titrate.  Calculate  the 
number  of  cc.  of  N/10  alkali  used  in  the  saponification  of  the  esters  as  ethyl  acetate; 
1  cc.  of  N/10  alkali  is  equivalent  to  0.0088  gram  of  ethyl  acetate.  Run  a  blank  using 
water  in  place  of  the  distillate  and  make  any  necessary  correction. 

ALDEHYDES— TENTATIVE. 

9  KBAGENTS. 

(a)  Aldehyde-free  alcohol. — Redistil  95%  alcohol  over  sodium  or  potassium  hy- 
droxid,  then  add  2-3  grams  per  liter  of  meta-phenylendiamin  hydrochlorid,  digest 
at  ordinary  temperature  for  several  days  (or  reflux  on  a  steam  bath  for  several 
hours)  and  then  distil  slowly,  rejecting  the  first  100  cc.  and  the  last  200  cc.  of  the 
distillate. 

(b)  Sulphite-fuchsin  solution. — Dissolve  0.50  gram  of  pure  fuchsin  in  500  cc.  of 
water,  then  add  5  grams  of  sulphur  dioxid  dissolved  in  water,  make  up  to  1  liter 
and  allow  to  stand  until  colorless.  This  solution  does  not  keep  indefinitely;  there- 
fore, prepare  in  small  quantities  and  keep  at  a  low  temperature. 

(C)  Standard  acetaldehyde  solution. — Prepare  according  to  the  directions  of  Vasey^ 
as  follows :  Grind  aldehyde  ammonia  in  a  mortar  with  anhydrous  ether  and  decant 
the  ether.  Repeat  this  operation  several  times,  then  dry  the  purified  salt  in  a 
current  of  air  and  finally  in  vacuo  over  sulphuric  acid.  Dissolve  1.386  grams  of  this 
purified  aldehyde  ammonia  in  50  cc.  of  95%  alcohol  by  volume,  add  22.7  cc.  of 
N/1  alcoholic  sulphuric  acid,  then  make  up  to  100  cc.  and  add  0.8  cc.  of  alcohol 
for  the  volume  of  the  ammonium  sulphate  precipitate.  Allow  the  mixture  to  stand 
overnight  and  filter.  This  solution  contains  1  gram  of  acetaldehyde  in  100  cc.  and 
will  retain  its  strength. 

The  standard  found  most  convenient  for  use  is  2  cc.  of  this  strong  aldehyde 
solution  diluted  to  100  cc.  with  50%  alcohol  by  volume.  One  cc.  of  this  solution 
is  equivalent  to  0.0002  gram  of  acetaldehyde.  This  solution  should  be  made  up 
fresh  every  day  or  so,  as  it  loses  strength. 

10  DETERMINATION. 

Determine  the  aldehyde  in  the  distillate,  prepared  as  directed  under  8.  Dilute 
5-10  cc.  of  the  distillate  to  50  cc.  with  aldehyde-free  alcohol  50%  by  volume,  add 
25  cc.  of  the  sulphite-fuchsin  solution  and  allow  to  stand  for  15  minutes  at  15°C. 
The  solutions  and  reagents  should  be  at  15°C.  when  they  are  mixed.  Prepare 
standards  of  known  strength  and  blanks  in  the  same  way.  The  comparison 
standards  found  most  convenient  for  use  contain  0.0001,  0.0002,  0.0004,  0.0005  and 
0.0006  gram  of  acetaldehyde. 

FURFURAL.— TENTATIVE. 

11  REAGENTS. 

(a)  Standard  furfural  solution. — Dissolve  1  gram  of  redistilled  furfural  in  100 
cc.  of  95%  alcohol  by  volume.     Standards  are  made  by  diluting  1  cc.  of  this  solu- 


XVII]  DISTILLED    LIQUORS  245 

tion   to   100  cc.  with  50%  alcohol   b}'  volume.     One  cc.  of  this  solution  contains 
0.0001  gram  of  furfural. 

(b)  Furfural-free  alcohol. — Prepare  as  directed  in  9  (a). 

1 2  DETERMINATION. 

Dilute  10-20  cc.  of  the  distillate,  as  prepared  under  8,  to  50  cc.  with  furfural- 
free  alcohol,  50%  by  volume.  Add  2  cc.  of  colorless  anilin  and  0.5  cc.  of  hydro- 
chloric acid  (sp.  gr.  1.125)  and  keep  for  15  minutes  in  a  water  bath  at  about  15°C. 
Prepare  standards  of  known  strength  and  blanks  in  the  same  way.  The  compari- 
son standards  found  most  convenient  for  use  contain  0.00005,  0.0001,  0.00015,  0.0002, 
0.00025  and  0.0003  gram  of  furfural. 

FUSEL  OIL.-TENTATIVE. 

13  REAGENTS. 

(a)  Purified  carbon  tetrachlorid. — Mix  crude  carbon  tetrachlorid  with  one  tenth 
its  volume  of  concentrated  sulphuric  acid,  shake  thoroughly  at  frequent  intervals 
and  allow  to  stand  overnight.  Wash  free  of  acid  and  impurities  with  tap  water. 
Remove  the  water,  add  an  excess  of  sodium  hydroxid  solution  and  distil  the  carbon 
tetrachlorid  from  it. 

(b)  Oxidizing  solution. — Disssolve  100  grams  of  potassium  dichromate  in  900  cc. 
of  water  and  add  100  cc.  of  concentrated  sulphuric  acid. 

14  DETERMINATION. 

(1)  To  100  cc.  of  the  sample  add  20  cc.  of  N/2  sodium  hydroxid  and  saponify  the 
mixture  by  boiling  for  an  hour  under  a  reflux  condenser;  or,  (2)  Mix  100  cc.  of  the 
liquor  with  20  cc.  of  N/2  sodium  hydroxid,  allow  to  stand  overnight  at  room  tem- 
perature and  distil  directly.  Connect  the  flask  with  a  distillation  apparatus,  distil 
90  cc,  add  25  cc.  of  water  and  continue  the  distillation  until  an  additional  25  cc.  are 
collected. 

Whenever  aldehydes  are  present  in  excess  of  15  parts  per  100,000,  add  to  the  dis- 
tillate 0.5  gram  of  meta-phenylendiamin  hydrochlorid,  reflux  for  an  hour,  distil 
100  cc,  add  25  cc.  of  water  and  continue  the  distillation  until  an  additional  25  cc. 
are  collected. 

Approximately  saturate  the  distillate  with  finely  ground  sodium  chlorid  and  add 
saturated  sodium  chlorid  solution  until  the  specific  gravity  is  1.10. 

Extract  this  salt  solution  4  times  with  the  purified  carbon  tetrachlorid,  using  40, 
30,  20  and  10  cc,  respectively,  and  wash  the  carbon  tetrachlorid  3  times  with  50 
cc.  portions  of  saturated  sodium  chlorid  solution,  and  twice  with  saturated  sodium 
sulphate  solution.  Then  transfer  the  carbon  tetrachlorid  to  a  flask  containing  50 
cc.  of  the  oxidizing  solution  and  boil  for  8  hours  under  a  reflux  condenser. 

Add  30  cc.  of  water  and  distil  until  only  about  20  cc.  remain;  add  80  cc.  of  water 
and  again  distil  until  15-20  cc.  are  left.  Neutralize  the  distillate  to  methyl  orange, 
and  titrate  with  N/10  sodium  hydroxid,  using  phenolphthalein  as  an  indicator. 
If  the  distillations  have  been  properly  conducted,  the  distillate  will  not  show  a 
marked  acid  reaction  to  methyl  orange.  Should  considerably  more  than  1  cc.  of 
N/10  alkali  be  consumed  at  this  point,  the  result  will  be  unreliable  and  the  deter- 
mination should  be  repeated.  One  cc.  of  N/10  sodium  hydroxid  is  equivalent  to 
0.0088  gram  of  amyl  alcohol. 

Rubber  stoppers  can  be  used  in  the  saponification  and  first  distillation,  but 
corks  covered  with  tinfoil  must  be  used  in  the  oxidation  and  second  distillation. 
Corks  and  tinfoil  must  be  renewed  frequently. 


246  METHODS    OF   ANALYSIS  [Chap. 

Conduct  a  blank  determination  upon  100  cc.  of  carbon  tetrachlorid  beginning 
the  blank  at  that  point  of  the  procedure  immediately  after  the  extraction  and  just 
before  the  washings  with  sodium  chlorid  and  sodium  sulphate  solutions. 

1 5  SUGARS.-TENTATIVE. 
Proceed  as  directed  under  XVI,  15,  16  or  17. 

METHYL  ALCOHOL. 

16  Trillal  Method^.— Tentative. 

To  50  cc.  of  the  sample  add  50  cc.  of  water  and  8  grams  of  lime  and  fractionate 
by  the  aid  of  Glinsky  bulb  tubes.  Dilute  the  first  15  cc.  of  the  distillate  to  150  cc, 
mix  with  15  grams  of  potassimn  dichromate  and  70  cc.  of  sulphuric  acid  (1  to  5), 
and  allow  to  stand  for  an  hour  with  occasional  shaking. 

Distil,  reject  the  first  25  cc.  and  collect  100  cc.  Mix  50  cc.  of  the  distillate  with 
1  cc.  of  redistilled  dimethylanilin,  transfer  to  a  stout,  tightly  stoppered  flask,  and 
keep  on  a  bath  at  70°-80°C.  for  3  hours  with  occasional  shaking.  Make  distinctly 
alkaline  with  sodium  hydroxid  solution,  and  distil  off  the  excess  of  dimethylanilin, 
stopping  the  distillation  when  25  cc.  have  passed  over. 

Acidify  the  residue  in  the  flask  with  acetic  acid,  shake  and  test  a  few  cc.  by  add- 
ing 4  or  5  drops  of  1%  suspension  of  lead  dioxid.  If  methyl  alcohol  is  present,  a 
blue  coloration  occurs  which  is  increased  by  boiling. 

Ethyl  alcohol  thus  treated  yields  a  blue  coloration  changing  immediately  to  green, 
later  to  yellow,  and  becoming  colorless  when  boiled. 

1 7  Riche  and  Bardy  Method^. — Tentative. 

The  following  method  for  the  detection  of  methyl  alcohol  in  commercial  spirit 
of  wine  depends  on  the  formation  of  methylanilin  violet  : 

Place  10  cc.  of  the  sample,  previously  redistilled  over  potassium  carbonate  if 
necessary,  in  a  small  flask  with  15  grams  of  iodin  and  2  grams  of  red  phosphorus. 
Keep  in  ice  water  for  10-15  minutes  until  action  has  ceased.  Distil  off,  on  a  water 
bath,  the  methyl  and  ethyl  iodids  formed  into  about  30  cc.  of  water.  Wash  with 
dilute  alkali  to  eliminate  free  iodin.  Separate  the  heavy,  oily  liquid  which  settles 
and  transfer  to  a  flask  containing  5  cc.  of  anilin.  If  the  action  be  too  violent,  place 
the  flask  in  cold  water;  if  too  slow,  stimulate  by  gently  warming  the  flask.  After  an 
hour  boil  the  product  with  water  and  add  about  20  cc.  of  15%  sodium  hydroxid 
solution;  when  the  bases  rise  to  the  top  as  an  oily  layer,  fill  the  flask  up  to  the  neck 
with  water  and  draw  them  off  with  a  pipette.  Oxidize  1  cc.  of  the  oily  liquid  by 
adding  10  grams  of  a  mixture  of  100  parts  of  clean  sand,  2  of  common  salt,  and  3 
of  cupric  nitrate;  mix  thoroughly,  transfer  to  a  glass  tube,  and  heat  to  90°C. 
for  8-10  hours.  Exhaust  the  product  with  warm  alcohol,  filter  and  make  up  to 
100  cc.  with  alcohol.  If  the  sample  of  spirits  is  pure,  the  liquid  has  a  red  tint,  but, 
in  the  presence  of  1%  of  methyl  alcohol,  it  has  a  distinct  violet  shade;  with  2.5% 
the  shade  is  very  distinct,  and  still  more  so  with  5%.  To  detect  more  minute  quan- 
tities of  methyl  alcohol,  dilute  5  cc.  of  the  colored  liquid  to  100  cc.  with  water,  and 
dilute  5  cc.  of  this  again  to  400  cc.  Heat  the  liquid  thus  obtained  in  a  porcelain 
dish  and  immerse  in  it  a  fragment  of  white  merino  (free  from  sulphur)  for  30  min- 
utes. If  the  alcohol  is  pure,  the  wool  will  remain  white,  but,  if  methyl  alcohol  is 
present,  the  fiber  will  become  violet,  the  depth  of  tint  giving  a  fairly  approximate 
indication  of  the  proportion  of  methyl  alcohol  present. 


XVII] 


DISTILLED    LIQUORS 


247 


18  Immersion  Refractometer  Method.     (Leach  and  Lythgoe*) — Tentative. 

Determine  by  the  immersion  refractometer  at  20°C.  the  refraction  of  the  distil- 
late obtained  in  the  determination  of  alcohol.  If,  on  reference  to  the  table  under 
19,  the  refraction  shows  the  percentage  of  alcohol  agreeing  with  that  obtained 
from  the  specific  gravity,  it  may  safely  be  assumed  that  no  methyl  alcohol  is  present. 
If,  however,  there  is  an  appreciable  amount  of  methyl  alcohol,  the  low  refractome- 
ter reading  will  at  once  indicate  the  fact.  If  the  absence  from  the  solution  of  re- 
fractive substances  other  than  water  and  the  alcohols  is  assured,  this  difference  in 
refraction  is  conclusive  of  the  presence  of  methyl  alcohol. 

The  addition  of  methyl  alcohol  to  ethyl  alcohol  decreases  the  refraction  in  direct 
proportion  to  the  amount  present;  hence  the  quantitative  calculation  is  readily 
made  by  interpolation  in  the  table  under  19,  using  the  figures  for  pure  ethyl  and 
methyl  alcohol  of  the  same  alcoholic  strength  as  the  sample. 

Example. — The  distillate  has  a  specific  gravity  of  0.97080,  corresponding  to 
18.38%  alcohol  by  weight,  and  has  a  refraction  of  35.8  at  20°C.  by  the  immersion 
refractometer;  by  interpolation  in  the  refractometer  table  the  readings  of  ethyl  and 
methyl  alcohol  corresponding  to  18.38%  alcohol  are  47.3  and  25.4,  respectivelv,  the 
difference  being  21.9;  47.3  -  35.8  =  11.5;  (11.5  -^  21.9)  100  =  52.5,  showing  that 
52.5%  of  the  total  alcohol  present  is  methyl  alcohol. 


19 


Table  18. 


Scale  readings 

of  the  Zeiss  immersion  refractometer  at  20°C.,  corresponding  to  each 

per  cent  hy  weight  of  methyl  and  ethyl  alcohols. 

PER 

SCAXE  READINGS 

PER 

SCALE   READINGS 

PER 

SCALE    READINGS 

PER 

SCALE    READINGS 

CENT 

CENT 
ALCO- 

CENT 
ALCO- 

CENT 
ALCO- 

ALCO- 

HOL 

Methyl 

Ethyl 

HOL 

Methyl 

Ethyl 

HOL 

Methyl 

Ethyl 

HOL 

Methyl 

Ethyl 

BT 

alco- 

alco- 

BY 

alco- 

alco- 

BY 

alco- 

alco- 

BY 

alco- 

alco- 

WEIGHT 

hol 

hol 

WEIGHT 

hol 

hol 

WEIGHT 

hol 

hol 

WEIGHT 

hol 

hol 

0 

14.5 

14.5 

25 

29.7 

60.1 

50 

39.8 

90.3 

75 

29.7 

101.0 

1 

14.8 

16.0 

26 

30.3 

61.9 

51 

39.7 

91.1 

76 

29.0 

101.0 

2 

15.4 

17.6 

27 

30.9 

63.7 

52 

39.6 

91.8 

77 

28.3 

100.9 

3 

16.0 

19.1 

28 

31.6 

65.5 

53 

39.6 

92.4 

78 

27.6 

100.9 

4 

16.6 

20.7 

29 

32.2 

67.2 

54 

39.5 

93.0 

79 

26.8 

100.8 

5 

17.2 

22.3 

30 

32.8 

69.0 

55 

39.4 

93.6 

80 

26.0 

100.7 

6 

17.8 

24.1 

31 

33.5 

70.4 

56 

39.2 

94.1 

81 

25.1 

100.6 

7 

18.4 

25.9 

32 

34.1 

71.7 

57 

39.0 

94.7 

82 

24.3 

100.5 

8 

19.0 

27.8 

33 

34.7 

73.1 

58 

38.6 

95.2 

83 

23.6 

100.4 

9 

19.6 

29.6 

34 

35.2 

74.4 

59 

3S.3 

95.7 

84 

22.8 

100.3 

10 

20.2 

31.4 

35 

35.8 

75.8 

60 

37.9 

96.2 

85 

21.8 

100.1 

11 

20.8 

33.2 

36 

36.3 

76.9 

61 

37.5 

96.7 

86 

20.8 

99.8 

12 

21.4 

35.0 

37 

36.8 

78.0 

62 

37.0 

97.1 

87 

19.7 

99.5 

13 

22.0 

36.9 

38 

37.3 

79.1 

63 

36.5 

97.5 

88 

18.6 

99.2 

14 

22.6 

38.7 

39 

37.7 

80.2 

64 

36.0 

98.0 

89 

17.3 

98.9 

15 

23.2 

40.5 

40 

38.1 

81.3 

65 

35.5 

98.3 

90 

16.1 

98.6 

16 

23.9 

42.5 

41 

38.4 

82.3 

66 

35.0 

98.7 

91 

14.9 

98.3 

17 

24.5 

44.5 

42 

38.8 

83.3 

67 

34.5 

99.1 

92 

13.7 

97.8 

18 

25.2 

46.5 

43 

39.2 

84.2 

68 

34,0 

99.4 

93 

12.4 

97.2 

19 

25.8 

48.5 

44 

39.3 

85.2 

69 

33.5 

99.7 

94 

11.0 

96.4 

20 

26.5 

50.5 

45 

39.4 

86.2 

70 

33.0 

100.0 

95 

9.6 

95.7 

21 

27.1 

52.4 

46 

39.5 

87.0 

71 

32.3 

100.2 

96 

8.2 

94.9 

22 

27.8 

54.3 

47 

39.6 

87.8 

72 

31.7 

100.4 

97 

6.7 

94.0 

23 

28.4 

56.3 

48 

39.7 

88.7 

73 

31.1 

100.6 

98 

3.5 

93.0 

24 

29.1 

58.2 

49 

39.8 

89.5 

74 

30.4 

100.8 

99 
100 

3.5 
2.0 

92.0 
91.0 



248  METHODS    OF   ANALYSIS 

20  COLORING  MATTERS.-TENTATIVE.. 
Proceed  as  directed  under  XI. 

21  WATER-INSOLUBLE  COLOR  IN  WHISKIES.— TENTATIVE. 

Evaporate  50  cc.  of  the  sample  just  to  dryness  on  a  steam  bath.  Take  up  with 
cold  water,  using  approximately  15  cc,  filter  and  wash  until  the  filtrate  amounts 
to  nearly  25  cc.  To  this  filtrate  add  25  cc.  of  absolute  alcohol,  or  26.3  cc.  of  95% 
alcohol  by  volume,  and  make  up  to  50  cc.  by  the  addition  of  water.  Mix  thor- 
oughly and  compare  in  a  colorimeter  with  the  original  material.  Calculate  from 
these  readings  the  per  cent  of  color  insoluble  in  water. 

COLORS  INSOLUBLE  IN  AMYL  ALCOHOL. 

22  Modified  Marsh  Method.— Tentative. 

Evaporate  50  cc.  of  whisky  just  to  dryness  on  a  steam  bath.  Dissolve  the 
residue  in  water  and  95%  alcohol  by  volume  and  make  to  a  volume  of  50  cc,  using 
a  total  volume  of  26.3  cc.  of  95%  alcohol.  Place  25  cc.  of  this  solution  in  a  separatory 
funnel  and  add  20  cc.  of  freshly  shaken  Marsh  reagent  (100  cc.  of  pure  amyl  alco- 
hol, 3  cc.  of  sirupy  phosphoric  acid  and  3  cc.  of  waterj,  shaking  lightly  so  as  not  to 
form  an  emulsion.  Allow  the  layers  to  separate  and  repeat  this  shaking  and  stand- 
ing twice  again.  After  the  layers  have  separated  completely  draw  off  the  lower 
or  aqueous  layer,  which  contains  the  caramel,  into  a  25  cc.  cylinder  and  make  up 
to  volume  with  50%  alcohol  by  volume.  Compare  this  solution  in  a  colorimeter 
with  the  untreated  25  cc.  Calculate  the  result  of  this  reading  to  the  per  cent  of 
color  insoluble  in  amyl  alcohol. 

CARAMEL. 

23  Amthor  Test  Modified  btj  Lasche^. — Tentative. 

Add  10  cc.  of  paraldehyde  to  5  cc.  of  the  sample  in  a  test  tube  and  shake.  Add 
absolute  alcohol,  a  few  drops  at  a  time,  shaking  after  each  addition  until  the  mixture 
becomes  clear.  Allow  to  stand.  Turbidity  after  10  minutes  is  an  indication  of 
caramel. 

BIBLIOGRAPHY. 

1  Vasey.     Guide  to  the  Analysis  of  Potable  Spirits.    1904,  p.  31. 

2  Abs.  Analyst,  1899,  24:  13;  Ibid.,  211,  212. 

*  Allen.     Commercial  Organic  Analysis.    4th  ed.,  1909-14,  1:  98. 
*J.  Am.  Chem.  Soc,  1905,  27:  9M. 
6  The  Brewer  Distiller,  May,  1903. 


XVin.  BEERS. 

1  PREPARATION  OF  SAMPLE.— TENTATIVE. 

Remove  carbon  dioxid  by  transferring  the  contents  of  the  bottle  to  a  large  flask 
and  shaking  vigorously  or  by  pouring  back  and  forth  between  beakers,  care  being 
taken  that  the  temperature  of  the  beer  is  not  below  20°C. 

2  COLOR.— TENTATIVE. 

Determine  the  depth  of  color  of  the  sample  in  a  j  inch  cell  with  a  Lovibond  tin- 
tometer, using  the  beer  scale.     Express  the  result  in  terms  of  a  i  inch  cell. 

3  SPECIFIC  GRAVITY.— TENTATIVE. 
Determine  the  specific  gravity  at  —^-^  b}'  means  of  a  pycnometer. 

4  ALCOHOL.— TENTATIVE. 
Determine  as  directed  under  XVI,  4. 

EXTRACT. 

5  Method  I.— Official. 

Measure  25  cc.  of  the  carbon  dioxid-free  beer  at  20°C.  into  a  tared,  flat-bottomed 
platinum  dish,  approximately  85  mm.  in  diameter,  and  evaporate  just  to  dryness 
on  a  steam  bath  and  heat  to  constant  weight  in  a  vacuum  oven  at  70°C. 

6  Method  11.— Tentative. 

The  immersion  refractometer  reading  of  the  beer  at  20°C.  minus  the  immersion 
refractometer  reading  of  the  distillate  at  20°C.  times  0.2571  equals  the  grams  of 
extract  in  100  cc.  of  beer. 

7  Method  III.— Tentative. 

Calculate  the  specific  gravity  of  the  dealcoholized  beer  by  the  following  formula: 
S  =  G4-  1- A  in  which 

S  =  the  specific  gravity  of  the  dealcoholized  beer; 
G  =  the  specific  gravity  of  the  beer;  and 

A  =  the  specific  gravity  of  the  distillate  obtained  in  the  determination 
of  alcohol. 

From  IX,  9,  ascertain  the  per  cent  by  weight  of  extract  in  the  dealcoholized  beer 
corresponding  to  the  value  of  S.  Multiply  the  figure  thus  obtained  by  S  to  ob- 
tain the  grams  of  extract  per  100  cc.  of  beer. 

8  EXTRACT  OF  ORIGINAL  WORT  (APPROXIMATE)  .—TENTATIVK. 
Calculate  the  grams  of  extract  per  100  cc.  in  the  original  wort  by  the  following 

formula: 

O  =  2A+  E  in  which 

O  =  extract  of  the  original  wort; 

A  =  alcohol  (grams  per  100  cc);  and 

E  =  extract  of  the  dealcoholized  beer  (grams  per  100  cc). 

249 


250  METHODS    OF   ANALYSIS  [Chap. 

9  DEGREE  OF  FERMENTATION.— TENTATIVE. 

Calculate  the  degree  of  fermentation  by  the  following  formula: 
^        100  X  2A 


O 


in  which 


D  =  degree  of  fermentation ; 

A  =  alcohol  (grams  per  100  cc);  and 

O  =  extract  of  original  wort. 

10  TOTAL  ACIDS.— TENTATIVE. 

Proceed  as  directed  under  XVI,  25.  Express  the  result  as  lactic  acid,  grams  per 
100  cc.  One  cc.  of  N/10  sodium  hydroxid  is  equivalent  to  0.0090  gram  of  lactic 
acid. 

1 1  VOLATILE  ACIDS.-TENTATIVE, 

Proceed  as  directed  under  XVI,  27.  Express  the  result  as  acetic  acid,  grams 
per  100  cc. 

12  REDUCING  SUGARS.-TENTATIVE. 

Dilute  25  cc.  of  the  carbon  dioxid-free  beer,  measured  at  20°C.,  with  water  to 
100  cc.  of  the  same  temperature.  Determine  the  reducing  sugars  in  25  cc.  of  this 
solution,  as  directed  under  VIII,  42.  Express  the  result  as  grams  of  anhydrous 
maltose  per  100  cc.  of  beer. 

1 3  DEXTRIN.— TENTATIVE. 

To  50  cc.  of  the  carbon  dioxid-free  beer  measured  at  20°C.,  add  15  cc.  of  hydro- 
chloric acid  (sp.  gr.  1.125),  dilute  to  200  cc,  attach  to  a  reflux  condenser  and  keep 
in  a  boiling  water  bath  for  2  hours.  Cool,  nearly  neutralize  with  sodium  hydroxid 
solution,  complete  to  a  volume  of  250  cc,  filter  and  determine  dextrose  as  directed 
under  VIII,  52  or  54.  From  the  number  of  grams  of  dextrose  per  100  cc.  of  beer, 
subtract  1.053  times  the  amount  of  maltose  as  found  in  12  and  multiply  the  re- 
mainder by  0.9  to  obtain  the  number  of  grams  of  dextrin  per  100  cc.  of  beer. 

14  DIRECT  POLARIZATION.— TENTATIVE. 

Read  the  polarization  of  the  original  sample  in  degrees  Ventzke  in  a  200  mm. 
tube  at  20°C.  If  the  beer  is  turbid,  clarify  by  shaking  with  alumina  cream,  filter 
and  correct  the  reading  for  dilution. 

1 5  GLYCEROL.-TENTATIVE. 

Proceed  as  directed  under  XVI,  8. 

16  ASH.-OFFICIAL. 

Evaporate  to  dryness  25  cc.  of  the  carbon  dioxid-free  sample,  measured  at  20°C., 
and  proceed  as  directed  under  VIII,  4. 

1  7  PHOSPHORIC  ACID.-TENTATIVE. 

To  25  cc.  of  the  carbon  dioxid-free  beer,  measured  at  20°C.,  add  20  cc.  of  2% 
calcium  acetate  solution,  evaporate  to  dryness  and  ignite  at  low  redness  to  a  white 
ash.  Add  10-15  cc.  of  boiling  nitric  acid  (1  to  9)  and  determine  phosphoric  acid 
(P2O5)  as  directed  under  I,  9. 


XVIII]  BEERS  251 

1 8  PROTEIN.-OFFICIAL. 

Measure,  at  20°C.,  25  cc.  of  the  carbon  dioxid-free  beer  into  a  Kjeldahl  digestion 
flask,  add  a  small  amount  of  tannin  to  prcvcMit  frothing,  evaporate  to  dryness,  de- 
termine nitrogen  as  directed  under  I,  18,  21  or  23,  multiply  the  result  by  6.25  and 
calculate  the  percentage  of  protein, 

1 9  PRESERVATIVES.-TENTATIVE. 
Proceed  as  directed  under  X. 

20  COLORING  MATTERS.— TENTATIVE. 
Proceed  as  directed  under  XI. 

21  METALS.-TENTATIVE. 

Proceed  as  directed  under  XII. 


XIX.  VINEGARS. 

(Unless  otherwise  noted,  express  results  as  grams  per  100  cc.) 

1  PHYSICAL  EXAMINATION.— TENTATIVE. 
Note  the  appearance,  color,  odor  and  taste. 

2  PREPARATION  OF  SAMPLE.-TENTATIVE. 

If  the  sample  is  turbid,  filter  before  proceeding  with  the  analysis. 

3  SPECIFIC  GRAVITY.— TENTATIVE. 
Determine  the  specific  gravity  at  '-^^  by  means  of  a  pycnometer. 

4  ALCOHOL.-TENTATIVE. 

Measure  100  cc.  of  the  sample  into  a  roimd-bottomed,  distillation  flask.  Make 
faintly  alkaline  with  saturated  sodium  hydroxid  solution,  add  a  small  piece  of 
paraflBn,  distil  almost  50  cc,  make  up  to  50  cc.  at  the  temperature  of  the  sample 
and  determine  the  specific  gravity  at  -ji— '  by  means  of  a  pycnometer.  Obtain  from 
XVI,  5,  the  per  cent  by  volume,  or  grams  per  100  cc,  noting  that  the  alcoholic 
strength  of  the  distillate  is  twice  that  of  the  original  vinegar. 

GLYCEROL.— TENTATIVE. 

5  REAGENTS. 

(a)  Strong  -potassium  dichromale  solution. — Dissolve  74.56  grams  of  dry,  recrystal- 
lized  potassium  dichromate  in  water,  add  150  cc.  of  concentrated  sulphuric  acid, 
cool  and  make  up  to  1  liter  at  20°C.  One  cc.  of  this  solution  is  equivalent  to  0.01 
gram  of  glycerol.  The  high  coefficient  of  expansion  of  this  strong  solution  necessi- 
tates its  preparation  at  exactly  20°C.  and  the  measurement  of  any  definite  volume 
at  the  same  temperature.  If  desired,  the  measurements  may  be  made  at  room 
temperature  by  means  of  a  weighing  burette,  the  volume  used  in  this  case  being 
ascertained  by  dividing  the  weight  of  the  solution  used  by  its  specific  gravity  at 
20  "C. 

4° 

(b)  Dilute  potassium  dichromate  solution. — Measure  25  cc.  of  the  strong  potas- 
sium dichromate  solution  at  exactly  20°C.  into  a  500  cc  volumetric  flask,  dilute  with 
water  and  make  up  to  the  mark  at  room  temperature.  Twenty  cc.  of  this  solution 
are  equivalent  to  1  cc.  of  (a). 

(C)  Ferrous  ammonium  sulphate  solution. — Dissolve  30  grams  of  crystallized  fer- 
rous ammonium  sulphate  in  water,  add  50  cc.  of  concentrated  sulphuric  acid,  cool 
and  dilute  at  room  temperature.  One  cc.  of  this  solution  is  approximately  equiva- 
lent to  1  cc  of  (b).  Its  value  changes  slightly  from  day  to  day  and  it  must  be 
standardized  against  (b)  whenever  used. 

(d)  Potassiiwi  ferricijanid  indicator. — Dissolve  1  gram  of  crystallized  potassium 
ferricyanid  in  50  cc.  of  water.     This  solution  must  be  freshly  prepared. 

(e)  Milk  of  lime. — Introduce  150  grams  of  calcium  oxid,  selected  from  clean,  hard 
lumps,  prepared  preferably  from  marble,  into  a  largo  porcelain  or  iron  dish,  slake 
with  water,  cool  and  add  suflicient  water  to  make  1  liter. 

253 


254  METHODS    OF    ANALYSIS  [Chap. 

(f)  Silver  carbonate. — Dissolve  0.1  gram  of  silver  sulphate  in  about  50  cc.  of  water, 
add  an  excess  of  sodium  carbonate  solution,  allow  the  precipitate  to  settle  and 
wash  with  water  several  times  by  decantation  until  the  washings  are  practically- 
neutral.     This  reagent  must  be  freshly  prepared  immediately  before  use. 

6  DETERMINATION. 

All  evaporations  should  be  made  on  a  ivaler  bath,  the  temperature  of  which  is  main- 
tained at  85°-90°C. 

Evaporate  100  cc.  of  the  vinegar  to  5  cc,  add  20  cc.  of  water  and  agarn  evaporate 
to  5  cc.  to  expel  acetic  acid.  Treat  the  residue  with  about  5  grams  of  fine  sand  and 
15  cc.  of  the  milk  of  lime  and  evaporate  almost  to  dryness,  with  frequent  stirring, 
avoiding  the  formation  of  a  dry  crust  or  evaporation  to  complete  dryness.  Treat 
the  moist  residue  with  5  cc.  of  water,  rub  into  a  homogeneous  paste,  then  add 
slowly  45  cc.  of  absolute  alcohol,  washing  down  the  sides  of  the  dish  to  remove 
adhering  paste,  and  stir  thoroughly.  Heat  the  mixture  on  a  water  bath,  with 
constant  stirring,  to  incipient  boiling,  transfer  to  a  suitable  vessel  and  centrifu- 
galize.  Decant  the  clear  liquid  into  a  porcelain  dish  and  wash  the  residue  with 
several  small  portions  of  hot  90%  alcohol  by  volume  by  aid  of  the  centrifuge. 
(If  a  centrifuge  is  not  available,  decant  the  liquid  through  a  fluted  filter  into  a 
porcelain  dish.  Wash  the  residue  repeatedly  with  small  portions  of  hot  90%  alco- 
hol, twice  by  decantation,  and  then  by  transferring  all  the  material  to  the  filter. 
Continue  the  washing  until  the  filtrate  amounts  to  150  cc.)  Evaporate  to  a  sirupy 
consistency,  add  10  cc.  of  absolute  alcohol  to  dissolve  this  residue  and  transfer  to 
a  50  cc.  glass-stoppered  cylinder,  washing  the  dish  with  successive  small  portions  of 
absolute  alcohol  until  the  volume  of  the  solution  amounts  to  20  cc.  Then  add 
3  portions  of  10  cc.  each  of  anhydrous  ether,  shaking  thoroughly  after  each  addi- 
tion. Let  stand  until  clear,  then  pour  off  through  a  filter,  and  wash  the  cylinder 
and  filter  with  a  mixture  of  2  volumes  of  absolute  alcohol  and  3  of  anhydrous  ether. 
If  a  heavy  precipitate  has  formed  in  the  cylinder,  centrifugalize  at  low  speed,  de- 
cant the  clear  liquid  and  wash  3  times  with  20  cc.  portions  of  the  alcohol-ether 
mixture,  shaking  the  mixture  thoroughly  each  time  and  separating  the  precipitate 
by  means  of  the  centrifuge.  Wash  the  paper  with  the  alcohol-ether  mixture,  and 
evaporate  the  filtrate  and  washings  on  the  water  bath  to  about  5  cc,  add  20  cc. 
of  water  and  again  evaporate  to  5  cc. ;  again  add  20  cc  of  water  and  evaporate  to  5 
CO.;  finally  add  10  cc.  of  water  and  evaporate  to  5  cc. 

These  evaporations  are  necessary  to  remove  all  the  ether  and  alcohol,  and,  when 
conducted  at  85°-90°C.,  result  in  no  loss  of  glycerol  if  the  concentration  of  the  latter 
is  less  than  50%. 

Transfer  the  residue  with  hot  water  to  a  50  cc.  graduated  flask,  cool,  add  the 
silver  carbonate,  prepared  from  0.1  gram  of  silver  sulphate,  shake  and  allow  to  stand 
10  minutes;  then  add  0.5  cc.  of  basic  lead  acetate  solution  [VIII,  13  (a)],  shake 
occasionally  and  allow  to  stand  10  minutes;  make  up  to  the  mark,  shake  well,  filter, 
rejecting  the  first  portion  of  the  filtrate,  and  pipette  25  cc.  of  the  clear  filtrate  into 
a  250  cc.  volumetric  flask. 

Add  1  cc.  of  concentrated  sulphuric  acid  to  precipitate  the  excess  of  lead  and 
then  30  cc.  of  the  strong  potassium  dichromate  solution.  Add  carefully  24  cc.  of 
concentrated  sulphuric  acid,  rotating  the  flask  gently  to  mix  the  contents  and  avoid 
violent  ebullition,  and  then  place  in  a  boiling  water  bath  for  exactly  20  minutes. 
Remove  the  flask  from  the  bath,  dilute,  cool  and  make  up  to  the  mark  at  room  tem- 
perature.    The  amount  of  strong  dichromate  solution  used  must  be  sufficient  to 


XIX]  VINEGARS  255 

leave  an  excess  of  about  12.5  cc.  at  the  end  of  the  oxidation,  the  amount  given  above 
(30  cc.)  being  sufficient  for  ordinary  vinegar  containing  about  0.35  gram  or  less  of 
glycerol  per  100  cc. 

Standardize  the  ferrous  ammonium  sulphate  solution  against  the  dilute  potas- 
sium dichromate  solution  by  introducing  from  the  respective  burettes  approxi- 
mately 20  cc.  of  each  of  the  2  solutions  into  a  beaker  containing  100  cc.  of  water. 
Complete  the  titration  using  the  potassium  ferricyanid  solution  as  an  outside  indi- 
cator. From  this  titration  calculate  the  volume  {F)  of  the  ferrous  ammonium  sul- 
phate solution  equivalent  to  20  cc.  of  the  dilute  and  also,  therefore,  to  1  cc.  of  the 
strong  dichromate  solution. 

In  place  of  the  dilute  dichromate  solution,  substitute  a  burette  containing  the 
oxidized  glycerol  with  an  excess  of  the  strong  dichromate  solution  and  ascertain  how 
many  cc.  are  equivalent  to  (F)  cc.  of  the  ferrous  ammonium  sulphate  solution  and 
also,  therefore,  to  1  cc.  of  the  strong  dichromate  solution.  Then  250  divided  by  this 
last  equivalent  equals  the  number  of  cc.  of  the  strong  dichromate  solution  pres- 
ent in  excess  in  the  250  cc.  flask  after  oxidation  of  the  glycerol. 

The  number  of  cc.  of  the  strong  dichromate  solution  added,  minus  the  excess 
found  after  oxidation,  multiplied  by  0.02  gives  the  grams  of  glycerol  per  100  cc.  of 
vinegar. 

7  SOLIDS.-TENTATIVE. 

Measure  10  cc.  of  the  sample  into  a  tared,  fiat-bottomed  platinum  dish  of  50 
mm.  bottom  diameter,  evaporate  on  a  boiling  water  bath  for  30  minutes,  and  dry 
for  exactly  2k  hours  in  a  water  oven  at  the  temperature  of  boiling  water.  Cool  in 
a  desiccator  and  weigh.  It  is  essential  that  the  size  and  shape  of  the  dish  and  the 
time  of  drying  be  followed  strictly. 

8  TOTAL  REDUCING  SUBSTANCES  BEFORE  INVERSION.— TENTATIVE. 

Proceed  as  directed  under  VIII,  25,  using  10  cc.  of  the  sample.  In  the  case  of 
malt  vinegar,  express  the  results  as  dextrose;  in  all  other  cases  as  invert  sugar. 

9  REDUCING  SUGARS  BEFORE  INVERSION  AFTER  EVAPORATION.— TENTATIVE. 

Evaporate  50  cc.  of  the  sample  on  the  water  bath  to  a  volume  of  5  cc.  Add  25 
cc.  of  water  and  again  evaporate  to  5  cc.  Transfer  to  a  100  cc.  volumetric  flask, 
make  up  to  the  mark,  and  proceed  as  directed  under  8,  using  a  quantity  equivalent 
to  10  or  20  cc.  of  the  sample. 

1 0  REDUCING  SUGARS  AFTER  INVERSION.-TENTATIVE. 

Proceed  as  directed  under  9.  After  the  last  evaporation  to  5  cc.  transfer  to  a 
100  cc.  volumetric  flask  with  70  cc.  of  water,  and  invert  as  directed  under  VIII, 
14.  Nearly  neutralize  with  sodium  hydroxid  solution,  make  up  to  the  mark  and 
proceed  as  directed  under  VIII,  25,  using  a  quantity  equivalent  to  10  or  20  cc.  of 
the  sample. 

11  LEAD  PRECIPITATE.-TENTATIVE. 

To  10  CC.  of  the  sample  in  a  test  tube,  add  2  cc.  of  20%  lead  acetate  solution, 
shake  and  let  stand  30  minutes.  Describe  the  precipitate  as  turbid,  light,  normal, 
heavy  or  very  heavy. 

12  .   POLARIZATION.-TENTATIVE. 

If  the  lead  precipitate  is  normal,  add  to  50  cc.  of  the  sample  5  cc.  of  basic  lead 
acetate  solution  [VIII,  13  (a)],  shake,  let  stand  30  minutes,  filter  and  polarize, 


256  METHODS    OF   ANALYSIS  [Chap. 

preferably  in  a  200  mm.  tube,  correcting  for  dilution.  If  basic  lead  acetate  gives 
only  a  turbidity,  add  to  the  sample,  already  treated  with  basic  lead  acetate,  10  cc. 
of  alumina  cream  [VIII,  13  (b)],  shake,  let  stand  30  minutes,  filter  and  polarize, 
correcting  for  dilution.  In  the  case  of  malt  vinegar,  treat  100  cc.  of  the  sample  with 
6  cc.  of  10%  phosphotungstic  acid  solution  and  filter.  To  50  cc.  of  the  filtrate  add 
5  cc.  of  the  basic  lead  acetate  solution,  filter  and  polarize,  correcting  the  reading 
obtained  for  dilution. 

1 3  ASH.-TENTATIVE. 

(a)  Measure  25  cc.  of  the  vinegar  into  a  tared  platinum  dish,  evaporate  to  dry- 
ness on  the  steam  bath  and  proceed  as  directed  under  VIII,  4. 

(b)  Evaporate  25  cc.  of  the  sample  to  dryness  as  directed  under  (a),  heat  in  a 
mufiJe  at  low  heat  to  expel  inflammable  gases,  treat  the  charred  portion  with  a  few 
cc.  of  water,  and  evaporate  to  dryness  on  a  water  bath;  replace  in  the  muffle  at  low 
redness  for  15  minutes,  and  continue  the  alternate  evaporation  and  heating  until 
a  white  or  gray  ash  is  obtained,  at  no  time  exceeding  a  dull  red  heat;  cool  in  a 
de.siccator  and  weigh. 

Useful  information  may  often  be  obtained  by  noting  the  odor  given  off  by  the 
solids  during  charring. 

14  SOLUBLE  AND  INSOLUBLE  ASH.— TENTATIVE. 
Treat  the  ash,  obtained  in  13,  as  directed  under  IX,  17. 

1 5  ALKALINITY  OF  THE  SOLUBLE  ASH.— TENTATIVE. 

Proceed  as  directed  under  IX,  18,  expressing  the  result  as  the  number  of  cc. 
of  N/10  hydrochloric  acid  required  to  neutralize  the  soluble  ash  from  100  cc.  of  the 
vinegar. 

1  3  SOLUBLE  AND  INSOLUBLE  PHOSPHORIC  ACID.— TENTATIVE. 

Determine  phosphoric  acid  in  the  water-soluble  and  water-insoluble  portions  of 
the  ash  as  directed  under  I,  9,  dissolving  the  water-insoluble  portion  in  about 
50  cc.  of  boiling  nitric  acid  (1  to  9).  Express  the  result  as  mg.  of  phosphorus 
pentoxid  (P2O6)  in  100  cc.  of  the  vinegar. 

1 7  TOTAL  ACIDS.-TENTATIVE. 

Dilute  10  cc.  of  the  sample  with  recently  boiled  and  cooled  water  until  it  appears 
very  slightly  colored,  and  titrate  with  N/2  alkali,  using  phenolphthalein  as  an 
indicator.     One  cc.  of  N/2  alkali  is  equivalent  to  0.030  gram  of  acetic  acid. 

1 8  FIXED  ACIDS.-TENTATIVE. 

Measure  10  cc.  of  the  vinegar  into  a  200  cc.  porcelain  casserole,  evaporate  just  to 
dryness,  add  5-10  cc.  of  water,  and  again  evaporate;  repeat  until  at  least  5  evapora- 
tions have  taken  place.  Add  about  200  cc.  of  recently  boiled  and  cooled  water  and 
titrate  with  N/10  alkali,  using  phenolphthalein  as  an  indicator.  One  cc.  of  N/10 
alkali  is  equivalent  to  0.0067  gram  of  malic  acid. 

19  VOLATILE  ACIDS.-TENTATIVE. 

To  obtain  the  volatile  acids  subtract  the  fixed  acids,  calculated  as  acetic  acid, 
from  the  total  acids. 


XIX]  VINEGARS  257 

20  COLOR.-TENTATIVE. 

Determine  the  depth  of  color  in  a  Lovibond  tintometer  by  good,  reflected  day- 
light, using  a  ^  inch  cell  and  the  brewer's  scale.  Express  the  result  in  terms  of 
a  -^  inch  cell. 

FORMIC  ACID. 

21  Fincke  Method}. — Tentative. 

Employ  the  apparatus  described  under  X,  39,  Fig.  6.  Introduce  100  cc.  of  the 
sample  into  flask  {A),  add  0.4-0.5  gram  of  tartaric  acid,  and  place  in  position  as 
shown  in  Fig.  6,  the  flask  (JB)  having  previously  been  charged  with  a  suspension  of 
15  grams  of  calcium  carbonate  in  100  cc.  of  water.  Heat  the  contents  of  flasks  (A) 
and  {B)  to  boiling  and  distil  with  steam  from  the  generator  (5),  the  vapor  passing 
first  through  the  sample  in  flask  {A),  then  through  the  boiling  suspension  of  cal- 
cium carbonate  in  flask  {B),  after  which  it  is  condensed  and  measured  in  the  re- 
ceiver (C).  Maintain  the  volume  of  liquid  in  flask  {B)  as  nearly  constant  as  pos- 
sible and  reduce  the  volume  of  the  sample  in  flask  (A)  to  30-40  cc.  by  heating  with 
small  Bunsen  flames,  the  distillation  being  continued  until  1  liter  of  distillate  is 
collected.  Disconnect  the  apparatus,  filter  the  calcium  carbonate  suspension,  and 
wash  the  calcium  carbonate  that  remains  on  the  paper  with  a  little  hot  water. 
Render  the  filtrate  faintly  acid  with  hydrochloric  acid,  add  10-15  cc.  of  mercuric 
chlorid  reagent  [  X,  38  (b)  ],  mix  and  heat  on  a  boiling  water  bath  for  2  hours.  Filter 
on  a  tared  Gooch,  wash  the  precipitate  thoroughly  with  cold  water  and  finally  with 
a  little  alcohol.  Dry  in  a  boiling  water  oven  for  30  minutes,  cool  in  a  desiccator, 
weigh,  and  calculate  the  weight  of  formic  acid  present  by  multiplying  the  weight 
of  the  precipitate  by  0.0975. 

22  ALCOHOL  PRECIPITATE.— TENTATIVE. 

Evaporate  100  cc.  of  the  vinegar  to  about  15  cc.  When  there  is  considerable 
sugar  in  the  vinegar,  if  the  sample  is  evaporated  to  too  low  a  volume,  a  gummy  or 
stringy  precipitate  is  formed  on  adding  the,alcohol  instead  of  a  flocculent  one.  When 
the  sugar  content  is  high,  therefore,  the  evaporation  should  not  be  carried  beyond 
20  cc.  To  this  residue  add  slowly  and  with  constant  stirring  200  cc.  of  95%  alcohol 
by  volume  and  allow  the  mixture  to  stand  overnight.  From  this  point  proceed 
as  directed  under  XIII,  18,  beginning  with  the  sentence,  "Filter  and  wash  with 
80%  alcohol  by  volume". 

23  PENTOSANS.-TENTATIVE. 

Proceed  as  directed  in  VIII,  84,  except  that  100  cc.  of  the  vinegar  and  43  cc.  of 
hydrochloric  acid  (sp.  gr.  1.19)  are  used  in  beginning  the  distillation. 

TARTARIC  ACID  AND  TARTRATES. 

24  Qualitative  Test.— Tentative. 

Evaporate  50  cc.  of  the  vinegar  in  a  porcelain  dish  to  a  volume  of  about  10  cc, 
filter  into  a  test  tube,  add  1  cc.  of  25%  calcium  chlorid  solution  and  2  cc.  of  50% 
ammonium  acetate  solution  and  allow  to  stand  overnight.  In  the  presence  of  tar- 
taric acid  a  deposit  of  calcium  tartrate  is  formed,  the  crystals  of  which  may  be 
identified  under  the  microscope  by  their  characteristic  form. 

25  TOTAL  TARTARIC  ACID.-TENTATIVE. 

Evaporate  200  cc.  of  the  sample  to  a  sirupy  consistency  to  remove  excess  of  acetic 
acid,  dilute  to  the  original  volume  with  water  in  a  volumetric  flask,  determine  the 


258  METHODS    OF   ANALYSIS 

acidity  as  directed  in  17,  and  determine  total  tartaric  acid  in  a  100  cc.  aliquot  as 
directed  under  XVI,  29,  except  that  20  cc.  of  alcohol  are  used  in  the  precipitation 
instead  of  15  cc. 

FREE  MINERAL  ACIDS. 

26  Logivood  Method'^. — Tentative. 

Prepare  an  extract  of  logwood  as  follows:  Pour  100  cc.  of  boiling  water  upon  2 
grams  of  fresh  logwood  chips,  allow  the  infusion  to  stand  for  a  few  hours  and  filter. 
Place  drops  of  the  liquid  on  a  porcelain  surface  and  dry  on  a  water  bath.  Add  to 
one  of  the  spots  a  drop  of  the  vinegar  to  be  tested  (after  concentration  if  desirable) 
and  evaporate  to  dryness.  A  yellow  tint  remains  if  free  mineral  acids  are  absent, 
a  red  tint  if  they  are  present. 

27  Methyl  Violet  Method. — Tentative. 

Add  5-10  cc.  of  water  to  5  cc.  of  vinegar  and,  after  mixing  well,  add  4  or  5  drops 
of  methyl  violet  solution  (1  part  of  methyl  violet  2B  in  10,000  parts  of  water).  A 
blue  or  green  coloration  indicates  the  presence  of  a  free  mineral  acid. 

28  Quantitative  Method.     (Hehner  Method) — Tentative. 

To  a  measured  amount  of  the  sample  add  a  measured  excess  of  standard  alkali, 
evaporate  to  dryness,  incinerate  and  titrate  the  ash  with  standard  acid,  using 
methyl  orange  as  an  indicator.  The  difference  between  the  number  of  cc.  of  alkali 
first  added  and  the  number  of  cc.  of  acid  needed  to  titrate  the  ash  represents  the  free 
mineral  acid  present. 

29  METALS.— TENTATIVE. 
Proceed  as  directed  under  XII. 


30  Qualitative  Test. — Tentative. 

Evaporate  100  cc.  of  the  vinegar  to  a  volume  of  about  15  cc.  Add  slowly  and 
with  constant  stirring  200  cc.  of  95%  alcohol  by  volume  and  allow  to  stand  over- 
night. The  precipitate  formed  should  be  tested  for  dextrin  by  the  optical  rotation 
and  color  reaction  with  iodin. 

SPICES  AND  ADDED  PUNGENT  MATERIALS. 

31  Qualitative  Test. — Tentative. 

Neutralize  exactly  a  portion  of  the  vinegar  and  test  by  taste  and  smell.  Agitate 
the  liquid  with  ether  in  a  separatory  funnel,  remove  and  evaporate  the  ethereal 
layer,  and  note  the  odor  and  taste  of  the  residue. 

32  COLORING  MATTERS.— TENTATIVE. 
Proceed  as  directed  under  XI.  • 

33  PRESERVATIVES.— TENTATIVE, 
Proceed  as  directed  under  X. 

BIBLIOGRAPHY. 

1  Z.  Nahr.  Genussm.,  1911,  21:  1;  22:  88. 

2  Allen.  Commercial  Organic  Analysis.  4th  ed.,  1909-14,  1:  503. 


XX.  FLAVORING  EXTRACTS. 
VANILLA  EXTRACT  AND  ITS  SUBSTITUTES. 

1  SPECIFIC  GRAVITY.-TENTATIVE. 

20°C 
Determine  the  specific  gravity  at  -p— '  by  means  of  a  pycnometer 

2  ALCOHOL.-OFFICIAL. 
Proceed  as  directed  under  XVII,  2  or  3. 

3  GLYCEROL.— TENTATIVE. 

Proceed  as  directed  under  XVI,  7,  8  or  9,  the  method  selected  depending  upon 
the  amount  of  sugar  present,  employing  an  amount  of  the  sample  containing  0.10- 
0.40  gram  of  glycerol. 

VANltLlN  AND  COUMARIN. 
Modified  Hess  and  Prescott  Method^. — Tentative. 

(This  method  is  not  applicable   to  concentrated  vanillin  and  coumarin 

preparations  in  which  the  amount  of  vanillin  and  coumarin  present 

exceeds  the  quantity  dissolved  by  100  cc.   of  water  at  20°C. 

In  such  cases  employ  a  smaller  amount  of  the  sample 

and  dilute  to  50  cc.) 

4  PREPARATION   OF   SOLUTION. 

Measure  50  cc.  of  the  extract  at  20°C.  into  a  250  cc.  beaker  with  marks  showing 
volumes  of  80  and  50  cc,  dilute  to  80  cc.  and  evaporate  to  50  cc.  on  a  water  bath  kept 
at  TO^C.  Dilute  again  with  water  to  80  cc.  and  evaporate  to  50  cc.  Transfer  to  a 
100  cc.  flask,  rinsing  the  beaker  with  hot  water;  add  25  cc.  of  8%  lead  acetate  solu- 
tion; make  up  to  the  mark  with  water,  shake  and  allow  to  stand  18  hours  (over- 
night) at  37°-40°C.  Decant  into  a  small,  dry  filter,  reserving  the  filtrate  for  the 
determination  of  vanillin  and  coumarin,  the  normal  lead  number,  6,  and  the 
residual  color,  14. 

5  DETERMINATION. 

Transfer  a  50  cc.  aliquot  of  the  filtrate  to  a  separatory  funnel  and  extract  with  4 
successive  15  cc.  portions  of  ether  (previously  washed  twice  with  an  equal  volume 
of  water  to  remove  alcohol).  Wash  the  combined  ether  solutions  4  or  5  times  with 
2%  ammonium  hydroxid  solution  (2%  NH3  by  weight),  using  10  cc.  the  first  time 
and  5  cc.  thereafter,  and  reserve  the  ether  solution  for  the  determination  of  cou- 
marin. Slightly  acidify  the  combined  ammoniacal  solutions  with  hydrochloric 
acid;  cool  and  extract  in  a  separatory  funnel  with  4  portions  of  washed  ether,  using 
about  40  cc.  altogether.  Evaporate  the  ethereal  solutions  at  room  temperature, 
dry  over  sulphuric  acid  and  weigh.  If  the  residue  is  considerably  discolored  or 
gummy,  re-extract  in  the  dry  state  with  boiling  petroleum  ether  (b.  p.  40°C.  or 
below)  not  less  than  15  times;  evaporate  the  solvent,  dry  and  weigh.  The  residue 
should  now  be  white,  crystalline  vanillin,  with  a  melting  point  of  approximately 

259 


260  METHODS    OF   ANALYSIS  [Chap. 

80°C.  A  small  amount  of  this  residue,  dissolved  in  2  drops  of  concentrated  hydro- 
chloric acid,  should  develop  a  pink  color  upon  the  addition  of  a  crystal  of  resorcin. 
Evaporate  at  room  temperature  the  original  ether  extract  of  the  sample,  from 
which  the  vanillin  has  been  removed  by  means  of  ammonium  hydroxid,  and  dry 
over  sulphuric  acid.  The  residue,  if  pure  coumarin,  should  melt  at  approximately 
67°C.  and  should  respond  to  Leach's  test  for  coumarin  as  follows:  A  small  por- 
tion of  the  residue,  dissolved  in  not  more  than  0.5  cc.  of  hot  water,  should  yield 
a  brown  precipitate  upon  the  addition  of  a  few  drops  of  N/10  iodin.  This  pre- 
cipitate finally  gathers  in  green  flecks,  leaving  a  clear,  brown  solution.  The 
reaction  is  especially  marked  if  the  reagent  is  applied  with  a  glass  rod  to  a  few 
drops  of  the  solution  on  a  white  plate  or  tile. 

$  NORMAL  LEAD  NUMBER'.— TENTATIVE. 

To  a  10  cc.  aliquot  of  the  filtrate  from  the  lead  acetate  precipitate,  as  obtained 
in  4,  add  25  cc.  of  water,  0.5-1.0  cc.  of  sulphuric  acid,  and  100  cc.  of  95%  alcohol  by 
volume.  Let  stand  overnight,  filter  on  a  Gooch  crucible,  wash  with  95%  alcohol, 
dry  at  a  moderate  heat,  ignite  at  low  redness  for  3  minutes,  taking  care  to  avoid 
the  reducing  flame,  and  weigh.  Conduct  a  blank  determination  employing  water 
containing  4  or  5  drops  of  glacial  acetic  acid  in  place  of  the  sample.  The  normal  lead 
number  is  calculated  by  the  following  formula: 

p  ^  100X0.6831(S-W)  ^  ^3^^^  ^^  _  ^^^  .^  ^,^^.^^ 

p  =  normal  lead  number  (grams  of  metallic  lead  in  the  precipitate  obtained 
from  ICO  cc.  of  the  sample); 

S  =  grams  of  lead  sulphate  corresponding  to  2.5  cc.  of  the  lead  acetate  solu- 
tion as  determined  in  a  blank  analysis;  and 

W  =  grams  of  lead  sulphate  obtained  in  10  cc.  of  the  filtrate  from  the  lead 
acetate  precipitate,  as  obtained  in  4. 

7  TOTAL  SOLIDS.-TENTATIVE. 

Proceed  as  directed  under  JX,  4,  employing  10  grams  of  the  sample. 

8  ASH.-OFFICL\L. 

Evaporate  10  grams  of  the  extract  and  determine  the  ash  as  directed  under 

vin,  4. 

9  ASH  CONSTITUENTS.— TENTATIVE. 
Proceed  as  directed  under  III  or  XXVIII,  21-28,  inclusive. 

10  SUCROSE.— TENTATIVE. 
Determine  as  directed  under  VIII,  14  or  18. 

VANILLA  RESINS. 

11  Qualitative  Test. — Tentative. 

Place  50  cc.  of  the  extract  in  a  glass  dish  and  evaporate  the  alcohol  on  a  water 
bath.  When  the  alcohol  is  removed,  make  up  to  about  the  original  volume  with 
hot  water.  If  alkali  has  not  been  used  in  the  manufacture  of  the  extract,  the  resins 
will  appear  as  a  flocculent  red  to  brown  residue.  Acidify  with  acetic  acid  to  free 
the  resins  from  the  bases,  separating  the  resins  completely  and  leaving  a  partly 
decolorized,  clear,  supernatant  liquid  after  standing  a  short  time.  Collect  the 
resins  on  a  filter,  wash  with  water  and  reserve  the  filtrate  for  further  tests. 


XX]  FLAVORING    EXTRACTS  261 

Place  a  portion  of  the  filter  with  the  attached  resins  in  a  few  cc.  of  dilute  potas- 
sium hydroxid  solution.  The  resins  are  dissolved,  giving  a  deep  red  solution; 
acidify,  and  the  resins  are  precipitated. 

Dissolve  a  portion  of  the  resins  in  alcohol.  To  one  portion  add  a  few  drops  of 
ferric  chlorid  solution;  to  another  portion  hydrochloric  acid;  neither  produces  any 
marked  change  in  color.  Most  resins,  however,  in  alcoholic  solution  give  color 
reactions  with  ferric  chlorid  or  hydrochloric  acid. 

To  a  portion  of  the  filtrate  obtained  above  add  a  few  drops  of  basic  lead  acetate 
solution.  The  precipitate  is  so  bulky  as  to  almost  solidify,  due  to  the  excessive 
amount  of  organic  acids,  gums  and  other  extractive  matter.  The  filtrate  from 
this  precipitate  is  almost  colorless. 

Test  another  portion  of  the  filtrate  from  the  resin  for  tannin  with  a  solution  of 
gelatin.  Tannin  is  present  in  varying  but  small  quantities,  but  should  not  be 
present  in  great  excess. 

12  METHYL  ALCOHOL.-TENTATIVE. 

Proceed  as  directed  under  X\1I,  16,  17  or  18,  using  the  distillate  from  tlie  de- 
termination of  alcohol,  2. 

13  COLOR  VALUE.— TENTATIVE. 

Pipette  2  cc.  of  the  extract  into  a  50  cc.  graduated  flask  and  make  up  to  the  mark 
with  a  mixture  of  equal  parts  of  95%  alcohol  by  volume  and  water.  Determine 
the  color  value  of  this  diluted  extract  in  terms  of  red  and  yellow  by  means  of  a 
Lovibond  tintometer,  using  a  1  inch  cell.  To  obtain  the  color  value  of  the  original 
extract,  multiply  the  figures  for  each  color  by  25. 

1 4  RESIDUAL  COLOR  AFTER  PRECIPITATION  WITH  LEAD  ACETATES-TENTATIVE. 

Determine  the  color  value,  in  terras  of  red  and  yellow,  of  the  filtrate  from  the 
lead  acetate  precipitate  as  obtained  in  4,  using  a  1  inch  Lovibond  cell.  Multiply 
the  reading  by  2  to  reduce  the  results  to  the  basis  of  the  original  extract.  If  the 
actual  reading  of  the  solution  is  greater  than  5  red  and  15  yellow,  as  may  happen 
if  the  extract  is  highly  colored  with  caramel,  a  ^  or  i  inch  cell  should  be  employed, 
and  the  readings  multiplied,  respectively,  by  4  or  8.  Divide  the  figures  for  red  and 
yellow,  respectively,  by  the  corresponding  figures  of  the  original  extract  and  mul- 
tiply the  quotients  by  100,  to  obtain  the  percentages  of  the  2  colors  remaining  in 
the  lead  acetate  filtrate. 

Calculate  also  the  ratio  of  red  to  yellow  in  both  extract  and  lead  acetate  filtrate. 

COLORS  INSOLUBLE  IN  AMYL  ALCOHOL. 

15  Modified  Man<h  MclJiod— Tentative. 

Proceed  as  directed  under  XVII,  22,  using  25  cc.  of  the  extract  and  shaking  with 
25  cc.  of  the  Marsh  reagent  instead  of  20  cc. 

16  COLORING  MATTERS  OTHER  THAN  CARAMEL.-TENTATIVE. 
Proceed  as  directed  under  XI. 

LEMON  AND  ORANGE  EXTRACTS. 

17  SPECIFIC  GRAVITY.-TENTATIVE. 
Determine  the  specific  gravity  at  "^^  by  means  of  a  pycnometer. 


262  METHODS   OF   ANALYSIS  [Chap. 

18  ALC  O  HDL.— TE  NTATIVE. 

Dilute  50  cc.  of  the  extract,  measured  at  20°C.,  with  water  to  about  200  cc,  allow 
the  mixture  to  stand  until  the  oil  separates  in  a  clear  layer  at  the  top,  or  centrifugal- 
ize,  then  make  up  to  the  mark,  using  the  lower  meniscus  of  the  oil.  Pour  the  mixture 
into  a  dry  Erlenmeyer  flask  containing  5  grams  of  light  magnesium  carbonate, 
stopper,  shake  well  and  filter  quickly  through  a  large,  dry,  folded  filter.  Intro- 
duce a  150  cc.  aliquot  of  the  filtrate,  measured  at  20°C.,  into  a  300-500  cc.  distilla- 
tion flask,  attach  the  flask  to  a  vertical  condenser  and  distil  almost  100  cc.  Com- 
plete the  volume  of  the  distillate  to  100  cc.  at  20''C.,  mix  well  and  determine  the 
specific  gravity  at  -p-^  •  Ascertain  the  corresponding  per  cent  of  alcohol  by  volume 
from  XVI,  5  and  multiply  the  result  thus  obtained  by  2f  to  obtain  the  percentage 
of  alcohol  by  volume  in  the  original  sample. 

19  GLYCEROL.— TENTATIVE. 

Proceed  as  directed  under  3. 

LEMON  AND  ORANGE  OILS. 

20  By  Polarization.     {Mitchell  Method)— Tentative. 

Without  diluting  polarize  the  extract  at  20°C.  in  a  200  mm.  tube.  Divide  the 
reading  in  degrees  Ventzke  by  3.2  in  the  case  of  lemon  extract  and  by  5.2  in  the 
case  of  orange  extract;  in  the  absence  of  other  optically  active  substances,  the  re- 
sult will  be  the  percentage  of  oil  by  volume.  A  small  amount  of  cane  sugar  is  occa- 
sionally present;  if  so,  determine  as  directed  under  28  and  correct  the  reading 
accordingly. 

21  By  Precipitation.     {Mitchell  Method) — Tentative. 

Pipette  20  cc.  of  the  extract  into  a  Babcock  milk  bottle,  add  1  cc.  of  hydrochloric 
acid  (1  to  1),  then  25-28  cc.  of  water  previously  warmed  to  60°C.,  mix,  let  stand 
in  water  at  60°C.  for  5  minutes,  centrifugalize  for  5  minutes,  fill  with  warm  water 
to  bring  the  oil  into  the  graduated  neck  of  the  flask,  again  centrifugalize  for  2  min- 
utes, place  the  flask  in  water  at  60°C.  for  a  few  minutes  and  note  the  per  cent  of  oil 
by  volume.  If  oil  of  lemon  is  present  in  amounts  over  2%,  add  0.4%  to  the  per- 
centage of  oil  noted  to  correct  for  the  solubility  of  the  oil.  If  less  than  2%  and 
more  than  1%  is  present,  add  0.3%  for  this  correction. 

When  the  extract  is  made  in  accordance  with  the  U.  S.  P.,  the  results  by  the 
methods  given  under  20  and  21  should  agree  within  0.2%. 

To  obtain  the  per  cent  by  weight  from  the  per  cent  by  volume,  as  found  by  either 
of  these  methods,  multiply  the  volume  percentage  by  0.86  in  the  case  of  lemon  ex- 
tracts, and  by  0.S5  in  the  case  of  orange  extracts,  and  divide  the  result  by  the  specific 
gravity  of  the  original  extract. 

TOTAL  ALDEHYDES. 
Chaxie  Method*. — Tentative. 

22  REAGENTS. 

(a)  Aldehyde-free  alcohol. — Allow  95%  alcohol  by  volume,  containing  5  grams 
of  meta-phenylendiamin  hydrochlorid  per  liter,  to  stand  for  24  hours  with  fre- 
quent shaking.  (Nothing  is  gained  by  previous  treatment  with  potassium  hy- 
droxid.)  Boil  under  a  reflux  condenser  for  at  least  8  hours,  longer  if  necessary, 
allow  to  stand  overnight  and  distil,  rejecting  the  first  10  and  the  last  5  per  cent 


XX]  FLAVORING    EXTRACTS  263 

which  come  over.  Store  in  a  dark,  cool  place  in  well  filled  bottles.  Twenty-five  cc. 
of  this  alcohol,  on  standing  20  minutes  at  14°-16°C.  with  20  cc.  of  the  sulphite  fuchsin 
solution,  should  develop  only  a  faint  pink  coloration.  If  a  stronger  color  is  de- 
veloped, repeat  the  treatment  with  meta-phenylndiamin  hydrochlorid  as  above. 

(b)  Sulphite-fuchsin  solution. — Dissolve  0.5  gram  of  fuchsin  in  250  cc.  of  water, 
add  an  aqueous  solution  of  sulphur  dioxid  containing  16  grams  of  the  gas,  allow  to 
stand  until  colorless,  or  nearly  so,  and  make  up  to  1  liter  with  water.  Let  stand  12 
hours  before  using  and  keep  in  a  refrigerator.  This  solution  is  liable  to  deteriorate 
and  should  be  reasonably  fresh  when  used. 

(C)  Standard  citral  solution. — Use  0.5  or  1  mg.  of  C.P.  citral  per  cc.  in  50%  alde- 
hyde-free alcohol. 

23  DETERMINATION. 

Weigh  approximately  25  grams  of  the  extract  in  a  stoppered  weighing  flask, 
transfer  to  a  50  cc.  flask  and  make  up  to  the  mark  at  room  temperature  with  alde- 
hyde-free alcohol.  Measure,  at  room  temperature,  2  cc.  of  this  solution  into  a 
comparison  tube.  Add  25  cc.  of  the  aldehyde-free  alcohol  (previously  cooled  to 
14°-16°C.),  then  20  cc.  of  the  sulphite-fuchsin  solution  (also  cooled)  and  finally  make 
up  to  the  50  cc.  mark  with  more  aldehyde-free  alcohol.  Mix  thoroughly,  stopper 
and  keep  at  14°-16°C.  for  15  minutes.  Prepare  a  standard  for  comparison  at  the 
same  time  and  in  the  same  manner,  using  2  cc.  of  the  standard  citral  solution,  and 
compare  the  colors  developed.  Calculate  the  amount  of  citral  present  and  re- 
peat the  determination,  using  a  quantity  sufficient  to  give  the  sample  approxi- 
mately the  strength  of  the  standard.  From  this  result  calculate  the  amount  of 
citral  in  the  sample.  If  the  comparisons  are  made  in  Nessler  tubes,  standards 
containing  1,  1.5,  2,  2.5,  3,  3.5,  and  4  mg.  of  citral,  may  be  prepared  and  the  trial 
comparison  made  against  these,  the  final  comparison  being  made  with  standards 
lying  between  1.5  and  2.5  mg.  with  0.25  mg.  increments. 

It  is  absolutely  essential  to  keep  the  reagents  and  comparison  tubes  at  the  re- 
quired temperature,  U^-IO'C.  Where  the  comparisons  are  made  in  a  bath  (this  being 
possible  only  where  the  bath  is  of  glass),  the  standards  should  be  discarded  within 
25  minutes  after  adding  the  sulphite-fuchsin  solution.  Give  samples  and  standards 
identical  treatment. 


Hiltner  Method^. — Tentative. 

24  REAGENTS. 

(a)  Meta-phenylendia/mn  hydrochlorid  solution. — Prepare  a  1%  solution  of  meta- 
phenylendiamin  hydrochlorid  in  95%  alcohol  by  volume.  Decolorize,  if  neces- 
sary, by  shaking  with  fuller's  earth  and  filter  through  a  double  filter.  The  solution 
should  be  bright  and  clear,  free  from  suspended  matter,  and  practically  colorless. 
Prepare  this  solution  only  for  immediate  use. 

(b)  Alcohol. — For  the  analj^sis  of  lemon  extracts,  90-95%  alcohol  by  volume 
should  be  used,  but  for  terpeneless  extracts,  40-50*^0  alcohol  by  volume  is  sufficient. 
Filter  to  remove  any  suspended  matter.  The  alcohol  need  not  be  purified  from 
aldehyde.  If  not  practically  colorless,  render  slightly  alkaline  with  sodium  hydroxid 
and  distil. 

25  '  DETERMINATICX. 

All  of  the  operations  may  be  carried  on  at  room  temperature.  Weigh  25  grams 
of  the  extract  into  a  50  cc.  graduated  flask  and  make  up  to  the  mark  with  alcohol. 


264  METHODS   OF  ANALYSIS  [Chap. 

Stopper  the  flask  and  mix  the  contents  thoroughly.  Pipette  2  cc.  of  this  solution 
into  a  colorimeter  tube;  add  10  cc.  of  the  meta-phenylendiamin  hydrochlorid  solu- 
tion and  complete  the  volume  to  50  cc.  (or  other  standard  volume)  with  alcohol. 
Compare  at  once  the  color  with  that  of  the  standard,  prepared  at  the  same  time, 
using  2  cc.  of  standard  citral  solution  and  10  cc.  of  the  meta-phenylendiamin  hy- 
drochlorid solution,  and  making  up  to  standard  volume  with  alcohol.  From  the 
result  of  this  first  determination,  calculate  the  amount  of  standard  citral  solution 
that  should  be  used  in  order  to  give  approximately  the  same  citral  strength  as  the 
sample  under  examination;  then  repeat  the  determination. 

29  TOTAL  SOLIDS.— OFFICIAL. 

Proceed  as  directed  under  XVII,  5,  employing  10  cc.  of  the  sample  measured 
at  20°C. 

27  ASH.-OFFICIAL. 

Ignite  the  residue  from  10  cc.  of  the  extract  as  directed  under  VIII,  4. 

28  SUCROSE.— TENTATIVE. 

Neutralize  the  normal  weight  of  the  extract,  evaporate  to  dryness,  wash  several 
times  with  ether,  dissolve  in  water  and  determine  as  directed  under  VIII,  14  or  18. 

29  METHYL  ALCOHOL.— TENTATIVE. 

Proceed  as  directed  under  XVII,  16,  17  or  18,  using  the  distillate  from  the 
determination  of  alcohol,  18. 

Coloring  Matters. 

30  general.-tentative. 
Proceed  as  directed  under  XI. 

3-1  lemon  and  orange  peel  color. 

Albrech  Method. — Tentative. 
Place  a  few  cc.  of  the  extract  in  each  of  2  test  tubes;  to  one,  add  slowly  3-4  vol- 
umes of  concentrated  hydrochloric  acid;  to  the  other,  several  drops  of  concentrated 
ammonium  hydroxid.     If  the  color  is  due  to  lemon  or  orange  peel  only  it  is  materi- 
ally deepened  by  such  treatment. 

LEMON  AND  ORANGE  OILS. 

32  specific  gravity.-tentative. 
Determine  the  specific  gravity  at  -^  by  means  of  a  pycnometer. 

33  INDEX  OF  REFRACTION.— TENTATIVE. 

Determine  the  index  of  refraction  with  any  standard  instrument,  making  the 
reading  at  20°C. 

34  OPTICAL  ROTATION.-TENTATIVE. 

Determine  the  rotation  at  20°C.  with  any  standard  instrument,  using  a  50  mm. 
tube  and  sodium  light.  The  results  should  be  stated  in  angular  degrees  on  a  100 
mm.  basis.  If  instruments  having  the  sugar  scale  are  used,  the  reading  on  orange 
oils  is  above  the  range  of  the  scale,  but  readings  may  be  obtained  by  the  use  of 


XX]  FLAVORING    EXTRACTS  265 

standard  laevo-rotatory  quartz  plates,  or  by  the  use  of  a  25  mm.  tube.  The  true 
rotation  cannot  be  obtained  by  diluting  the  oil  with  alcohol  and  correcting  the 
rotation  in  proportion  to  the  dilution. 

CITRAL. 

Kleher  Method^. — Tentative. 

35  REAGENTS. 

(a)  Phenylhydrazin  solution. — Prepare  a  10%  solution  in  absolute  alcohol.  A 
sufficiently  pure  product  can  be  obtained  by  distilling  the  commercial  article, 
rejecting  the  first  portions  coming  over  which  contain  ammonia. 

(b)  N/2  hydrochloric  acid. 


DETERMINATION. 


36 

Weigh  15  grams  of  the  sample  into  a  small,  glass-stoppered  flask;  add  10  cc.  of  the 
phenylhydrazin  solution.  Allow  to  stand  30  minutes  at  room  temperature,  titrate 
with  N/2  hydrochloric  acid,  using  either  methyl  or  ethyl  orange  as  an  indicator. 
Titrate  similarly  10  cc.  of  the  phenylhydrazin  solution.  The  difference  in  the  num- 
ber of  cc.  of  N/2  acid  used  in  these  2  titrations,  multiplied  by  the  factor  0.076,  gives 
the  weight  of  citral  in  the  sample.  If  difficulty  is  experienced  in  detecting  the  end 
point  of  the  reaction,  titrate  until  the  solution  is  distinctly  acid,  transfer  to  a  sepa- 
ratory  funnel,  and  draw  off  the  alcoholic  portion.  Wash  the  oil  with  water,  adding 
the  washings  to  the  alcoholic  solution,  titrate  back  with  N/2  alkali  and  make  the 
necessary  corrections. 

37  Hiltner  Method^.— Tentative. 

Weigh  2  grams  of  lemon  oil  or  8  grams  of  orange  oil  into  a  100  cc.  graduated  flask, 
dilute  to  the  mark  with  95%  alcohol  by  volume  and  proceed  as  under  25,  using 
2  cc.  of  the  dilute  solution  for  the  comparison. 

TOTAL  ALDEHYDES. 

38  Chace  Method. — Tentative. 

Weigh  a  small  quantity  of  the  sample  into  a  small,  stoppered  flask  and  dilute 
with  aldehyde-free  alcohol  in  the  proportion  of  2  grams  of  lemon  oil  or  4  grams  of 
orange  oil  to  100  cc.  of  solution.  Determine  the  total  aldehydes  as  directed  under 
23,  expressing  the  result  as  citral. 

39  PHYSICAL  CONSTANTS  OF  THE  10  PER  CENT  DISTILL  ATE". -TENTATIVE. 

Place  50  cc.  of  the  sample  in  a  3-bulb  Ladenburg  flask  having  the  main  bulb  6 
cm.  in  diameter  and  of  120  cc.  capacity  and  the  condensing  bulbs  of  the  following 
dimensions:  3.5  cm.,  3  cm.,  2.5  cm.;  the  distance  from  the  bottom  of  the  flask  to 
the  opening  of  the  side  arm  should  be  20  cm.  Distil  the  oil  at  the  rate  of  2  cc.  per 
minute  until  5  cc.  have  been  distilled.  Determine  the  refractive  index  and  rotation 
of  this  distillate  as  directed  in  33  and  34. 

40  PINENE. 

Chace  Method^. — Tentative. 

Mix  the  10%  distillate,  obtained  in  39,  with  5  cc.  of  glacial  acetic  acid;  cool  the 
mixture  thoroughly  in  a  freezing  bath  and  add  10  cc.  of  ethyl  nitrite.     Then  add 


266  METHODS    OF   ANALYSIS  [Chap, 

slowly,  with  constant  stirring,  2  cc.  of  hydrochloric  acid  (2  to  1).  Keep  the  mixture 
in  the  freezing  bath  15  minutes.  Filter  off  the  crystals  formed,  using  suction,  and 
wash  with  95%  alcohol  by  volume.  Return  the  combined  filtrate  and  washings 
to  the  freezing  bath  for  15  minutes.  Filter  off  the  crystals  formed,  using  the  origi- 
nal filter  paper.  Wash  the  combined  crops  of  crystals  thoroughly  with  alcohol. 
Dry  at  room  temperature  and  dissolve  in  a  minimum  amount  of  chloroform.  Add 
methyl  alcohol  to  the  chloroform  solution,  a  little  at  a  time,  until  the  nitroso- 
chlorids  crystallize  out,  mount  the  separated  and  dried  crystals  in  olive  oil  and 
examine  under  the  microscope.  Pinene  nitroso-chlorid  crystals  have  irregular 
pyramidal  ends  while  limonene  nitroso-chlorid  crystallizes  in  needles. 

ALMOND  EXTRACT. 

41  ALCOHOL.-TENTATIVE. 

Inasmuch  as  almond  extract  usually  contains  only  about  1%  of  almond  oil 
the  alcohol  can,  in  most  cases,  be  calculated  from  the  specific  gravity  of  the 
extract.  If  the  extract  is  high  in  solids,  determine  the  alcohol  as  follows:  Add  25 
cc.  of  the  extract,  measured  at  20°C.,  to  75  cc.  of  saturated  sodium  chlorid  solution 
in  a  separatory  funnel  and  extract  twice  with  50  cc.  portions  of  petroleum  ether 
(b.  p.  40°-60°C.).  Collect  the  petroleum  ether  extract  in  a  second  separatory  fun- 
nel and  wash  twice  with  2  portions  (25  cc.)  of  saturated  brine.  Combine  the  origi- 
nal salt  solution  with  the  washings;  add  a  little  powdered  pumice  and  distil  into  a 
100  cc.  flask.  When  almost  100  cc.  have  been  distilled,  make  up  to  the  mark  with 
v/atcr  at  20°C.  and  determine  alcohol  from  the  specific  gravity,  as  directed  under 
XVII,  4. 

BENZALDEHYDE.— TENTATIVE. 

42  REAGENT. 

Phenylhydrazin  solution. — Add  1.5  cc.  of  glacial  acetic  acid  to  20  cc.  of  water  and 
mix  with  1  cc.  of  phenylhydrazin. 

43  DETERMINATION. 

Measure  out  2  portions  of  10  cc.  each  of  the  extract  into  300  cc.  Erlenmeyer 
flasks  and  add  10  cc.  of  the  phenylhydrazin  solution  to  1  flask  and  15  cc.  to  the 
other.  Allow  to  stand  overnight  in  a  dark  place,  add  200  cc.  of  water  and  filter  on 
a  tared  Gooch  crucible,  provided  with  a  thin  layer  of  asbestos.  Wash  first  with  cold 
water,  finally  with  10  cc.  of  10%  alcohol,  and  dry  for  3  hours  in  a  vacuum  oven  at 
70°C.,  or  to  constant  weight  over  sulphuric  acid.  The  weight  of  the  precipitate 
multiplied  by  the  factor  5.408  gives  the  weight  of  benzaldehyde  in  100  cc.  of  the 
sample.  If  duplicate  determinations  do  not  agree,  repeat  the  operation  using  a 
larger  quantity  of  the  phenylhydrazin  solution. 

HYDROCYANIC  ACID. 

44  Qualitative  Test. — Tentative. 

Add  several  drops  of  ferrous  sulphate  solution  and  a  single  drop  of  ferric  chlorid 
solution  to  several  cc.  of  the  extract.  Mix  thoroughly,  add  sodium  hydroxid  solu- 
tion, drop  by  drop,  until  no  further  precipitate  forms  and  then  dilute  hydro- 
chloric acid  to  dissolve  the  precipitated  hydroxids.  In  the  presence  even  of  small 
amounts  of  hydrocyanic  acid,  a  Prussian  blue  coloration  or  suspension  will  develop. 


XX] 


FLAVORING    EXTRACTS 


267 


45  Quantitative  Method. — Tentative. 

(In  the  absence  of  chlorids.) 
Measure  25  cc.  of  the  extract  into  a  small  flask  and  add  5  cc.  of  freshly  precipi- 
tated magnesium  hydroxid  (chlorin-free).     Titrate  with  N/10  silver  nitrate  solu- 
tion,  using  potassium   chromate  as  an  indicator;   1  cc.  of  N/10  silver  nitrate  is 
equivalent  to  0.00268  gram  of  hydrocyanic  acid. 

NITROBENZOL. 

46  Qualitative  Test. — Tentative. 

Boil  a  few  cc.  of  the  extract  with  some  zinc  dust  and  acetic  acid  and  filter.  Add 
to  the  filtrate  a  drop  of  chloroform,  make  strongly  alkaline  with  sodium  hydroxid 
solution  and  heat.  The  presence  of  nitrobenzol  in  the  original  extract  is  indicated 
by  the  development  of  the  characteristic  odor  of  phenylisonitrile. 

CASSIA,  CINNAMON  AND  CLOVE  EXTRACTS. 

47  ALCOHOL.-TENTATIVE. 
Determine  as  directed  under  41 . 


48 


Hortvet  and  West  Method^.— Tentatii 


Transfer  10  cc.  of  the  extract  to  a  separatory  funnel,  add  30  cc.  of  water,  acidify 
with  1  cc.  of  hydrochloric  acid  (1  to  1)  and  extract  3  times  with  ether,  using  not 
less  than  100  cc.  altogether.  Wash  the  combined  ether  solutions  twice  with  water 
and,  in  the  case  of  cinnamon  extract,  dry  by  shaking  with  a  small  amount  of  granu- 
lated calcium  chlorid.  Transfer  to  a  tared,  wide-mouthed  weighing  bottle  and  evap- 
orate the  ether  as  rapidly  as  possible  on  a  boiling  water  bath,  rotating  the  liquid 
upon  the  sides  of  the  bottle  in  order  to  rid  the  residual  oil  of  traces  of  ether.  Weigh 
the  residue  and  divide  the  weight  by  the  specific  gravity  of  the  oil  in  order  to  ob- 
tain the  per  cent  of  oil  by  volume.  In  the  case  of  clove  oil,  allow  the  weighing  bottle 
to  remain  in  the  balance  case  until  the  usual  film  of  moisture  has  evaporated.  The 
time  of  weighing,  however,  should  not  be  delayed  over  3  minutes. 

Determine  the  refractive  index  of  the  residual  oils  at  20°C. 

Dissolve  a  drop  of  the  oil  in  several  drops  of  alcohol  and  add  a  drop  of  ferric 
chlorid  solution.  The  following  tabulation  gives  the  specific  gravity,  refractive 
index  at  20°C.  and  color  reaction  with  ferric  chlorid  solution: 


OIL 

SPECIFIC  QRAVITT 

REFRACTIVE  I.VDEX 
AT  20°C. 

COLOR  REACTION 

WITH  FERRIC 

CHLORID  SOLUTION 

1.05 
1.03 
1.055 

1.58.5-1.600 
1.590-1.599 
1.560-1.565 

Cinnamon 

Green 

Cloves ... 

Deep  blue 

GINGER   EXTRACT. 

49  ALCOHOL.-TENTATIVE. 
Determine  as  directed  under  XVII,  4. 

50  SOLIDS.-TENTATIVE. 

Evaporate  10  cc.  of  the  extract  nearly  to  dryness  on  a  water  bath,  dry  for  2  hours 
in  a  water  oven  and  weigh. 


268  METHODS   OF   ANALYSIS  [Chap. 

GINGER. 

51  Seeker  Method. — Tentative. 

Dilute  10  cc.  of  the  extract  to  30  cc,  evaporate  to  20  cc,  decant  into  a  separa- 
tory  funnel  and  extract  with  an  equal  volume  of  ether.  Allow  the  ether  to  evaporate 
spontaneously  in  a  porcelain  dish,  and  to  the  residue  add  5  cc.  of  75%  sulphuric  acid 
and  about  5  mg.  of  vanillin.  Allow  to  stand  15  minutes  and  add  an  equal  volume 
of  water;  in  the  presence  of  ginger  extract  an  azure  blue  color  develops. 

CAPSICUM. 

52  La  Wall  Method  Modified  by  Doyle. — Tentative. 

To  10  cc.  of  the  extract  add  cautiously  dilute  sodium  hydroxid  solution  until  the 
solution  reacts  very  slightly  alkaline  with  litmus  paper.  Evaporate  at  about  TO'C. 
to  approximately  one  fourth  the  original  volume,  render  slightl}^  acid  with  dilute 
sulphuric  acid,  testing  with  litmus  paper.  Transfer  to  a  separatory  funnel,  rinsing 
the  dish  with  water,  and  extract  with  an  equal  volume  of  ether,  avoiding  emulsi- 
fication  by  shaking  the  funnel  gently  1-2  minutes.  Draw  off  the  lower  layer  and 
wash  the  ether  extract  once  with  about  10  cc.  of  water.  Transfer  the  washed  ether 
extract  to  a  small  evaporating  dish,  render  decidedly  alkaline  with  N/2  alcoholic 
potassium  hydroxid  and  evaporate  at  about  70°C.  until  the  residue  is  pasty;  then 
add  about  20  cc.  more  of  N/2  alcoholic  potash  and  allow  to  stand  on  a  steam  bath 
until  the  gingerol  is  completely  saponified  (about  30  minutes).  Dissolve  the  residue 
in  a  little  water  and  transfer  with  water  to  a  small  separatory  funnel.  The  volume 
should  not  exceed  50  cc.  Extract  the  alkaline  solution  with  an  equal  volume  of 
ether.  Wash  the  ether  extract  repeatedly  with  small  amounts  of  water  until  no 
longer  alkaline  to  litmus.  Transfer  the  washed  extract  to  a  small  evaporating  dish, 
and  allow  the  ether  to  evaporate  spontaneously.  Finally  test  the  residue  for  capsi- 
cum by  moistening  the  tip  of  the  finger,  rubbing  it  on  the  bottom  and  sides  of  the 
dish,  and  then  applying  the  finger  to  the  end  of  the  tongue.  A  hot,  stinging  or 
prickly  sensation,  which  persists  for  several  minutes,  indicates  capsicum  or  other 
foreign  pungent  substances. 

PEPPERMINT,  SPEARMINT  AND  V/INTERGREEN  EXTRACTS. 

53  ALCOHOL.— TENTATIVE. 
Proceed  as  directed  under  41 . 

OIL. 

54  Howard  Method^''  Modified. — Tentative. 

Pipette  10  cc.  of  the  extract  into  a  Babcock  milk  bottle,  add  1  cc.  of  carbon  di- 
sulphid,  mix  thoroughly,  then  add  25  cc.  of  cold  water  and  1  cc.  of  concentrated 
hydrochloric  acid.  Close  the  mouth  of  the  bottle  and  shake  vigorously;  centrif- 
ugalize  for  6  minutes  and  remove  all  but  3-4  cc.  of  the  supernatant  liquid,  which 
should  be  practically  clear,  by  aspirating  through  a  glass  tube  of  small  bore. 
Connect  the  stem  of  the  bottle  with  a  filter  pump,  immerse  the  bottle  in  water  kept 
at  approximately  70°C.  for  3  minutes,  remove  from  the  bath  every  15  seconds  and 
shake  vigorously.  Continue  in  the  same  manner  for  45  seconds,  using  a  boiling  water 
bath.  Remove  from  the  bath  and  shake  while  cooling.  Disconnect  from  the  suc- 
tion and  fill  the  bottle  to  the  neck  with  saturated  salt  solution  at  room  temperature, 
centrifugalize  for  2  minutes  and  read  the  volume  of  the  separated  oil  from  the  top 
of  the  meniscus.     Multiply  the  reading  by  2  to  obtain  the  per  cent  of  oil  by  volume. 


XX]  FLAVORING    EXTRACTS  269 

In  the  case  of  wintergreen,  use  as  a  floating  medium  a  mixture  of  1  volume  of  con- 
centrated sulphuric  acid  and  3  of  saturated  sodium  sulphate  solution. 

METHYL  SALICYLATE  IN  WINTERGREEN  EXTRACT. 

55  Hortvet  and  West  Method'^  Modified. — Tentative. 

Mix  10  cc.  of  the  extract  with  10  cc.  of  10%  potassium  hydroxid  solution.  Heat 
on  the  steam  bath  until  the  volume  is  reduced  about  one  half,  add  a  distinct  excess 
of  hydrochloric  acid  (1  to  1),  cool  and  extract  with  3  portions  of  ether,  40,  30  and 
20  cc,  respectively.  Filter  the  extract  through  a  dry  filter  into  a  weighed  dish,  wash 
the  paper  with  10  cc.  of  ether  and  allow  the  filtrate  and  washings  to  evaporate  spon- 
taneously. Dry  in  a  desiccator  containing  sulphuric  acid  and  weigh.  Multiply 
the  weight  of  salicylic  acid  so  found  by  9.33  to  obtain  the  per  cent  by  volume  of 
wintergreen  oil  in  the  sample. 

ANISE  AND  NUTMEG  EXTRACTS. 
OIL. 

56  Hortvet  and  West  Method^.— Tentative. 

To  10  cc.  of  the  extract  in  a  Babcock  milk  bottle  add  1  cc.  of  hydrochloric  acid 
(1  to  1),  then  sufficient  half  saturated  salt  solution,  previously  heated  to  60°C.,  to 
fill  the  flask  nearly  to  the  neck.  Cork  and  let  stand  in  water  at  60°C.  for  about  15 
minutes,  rotate  occasionally  and  centrifugalize  for  10  minutes  at  about  800  revo- 
lutions per  minute.  Add  brine  till  the  oil  rises  into  the  neck  of  the  bottle,  and  again 
centrifugalize  for  10  minutes.  If  the  separation  is  not  satisfactory,  or  the  liquid  is 
not  clear,  cool  to  about  10°C.  and  centrifugalize  for  an  additional  10  minutes. 
Multiply  the  reading  by  2  to  obtain  the  percentage  of  oil  by  volume. 

BIBLIOGRAPHY. 

1  J.  Am.  Chem.  Soc,  1899,  21:  256;  1902,  24:  1128;  1905,  27:  719. 

2  U.  S.  Bur.  Chem.  Bull.  132,  p.  109. 

3  Ibid.,  152,  p.  146. 

*  J.  Am.  Chem.  Soc,  1906,  28:  1472. 

5  U.  S.  Bur.  Chem.  Bull.  132,  p.  102. 

« Ibid.,  137,  p.  72. 

^  Schimmel  and  Co.  Semi-annual  Report.     Oct.  1898,  p.  41. 

8  U.  S.  Bur.  Chem.  Circ  46,  p.  9. 

9  J.  Ind.  Eng.  Chem.,  1909,  1:  84. 
i«Ibid.,  1911,  3:252. 


XXI.     MEAT  AND  MEAT  PRODUCTS. 

MEAT. 

1  PREPARATION  OF  SAMPLE.-TENTATIVE. 

In  the  case  of  fresh  meat,  separate  the  sample  as  completely  as  possible  from  the 
bones  and  pass  through  a  sausage  mill  rapidly  and  repeatedly  until  thoroughly 
mixed  and  macerated.  Chill  the  sample  to  prevent  decomposition  and  begin  all 
determinations  as  soon  as  practicable  after  the  sample  is  prepared. 

In  the  case  of  canned  meats,  pass  the  entire  contents  of  a  can  through  a  sausage 
mill  as  directed  above.  Remove  sausage  from  the  casings  and  mix  by  repeated 
grinding  in  a  sausage  mill.  Dry  the  portion  of  the  sample,  which  is  not  needed 
for  analysis,  either  in  vacuo  or  by  evaporating  with  alcohol,  extract  the  fat  with 
gasoline  (b.  p.  below  60°C.),  allow  the  gasoline  to  evaporate  spontaneously  and 
expel  the  last  traces  by  heating  for  a  short  time  on  the  steam  bath.  Do  not 
heat  the  meat  or  separated  fat  longer  than  necessary,  owing  to  the  tendency  of  the 
latter  to  decompose.  Reserve  the  fat  for  examination  according  to  the  methods 
given  under  XXIII.  Keep  the  fat  in  a  cool  place  and  complete  the  examination 
before  the  fat  becomes  rancid. 

2  MOISTURE.-TENTATIVE. 

Proceed  as  directed  under  VIII,  2  or  3,  using  the  latter  method  in  cases  in  which 
it  is  desired  to  employ  the  dried  sample  for  further  determinations. 

3  ASH.-OFFICIAL. 
Proceed  as  directed  under  VIII,  4. 

4  CRUDE  FAT  OR  ETHER  EXTRACT.— OFFICIAL. 

Proceed  as  directed  under  VIII,  10. 

5  TOTAL  PHOSPHORUS.-TENTATIVE. 

Destroy  the  organic  matter  as  directed  under  I,  5  (a),  (b),  (C)  or  (d)  and  proceed 
as  directed  under  I,  6  or  9. 

WATER-SOLUBLE  PHOSPHORUS'.— TENTATIVE. 

6  PREPARATION   OF  SOLUTIONS. 

(a)  Cold  water  extract  of  flesh. — Weigh  out  10-12  grams  of  fresh  muscle  and  di- 
vide equally  between  2  small  beakers.  Moisten  the  sample  with  a  few  cc.  of  water, 
and  break  up  the  lumps  with  a  glass  rod.  Add  50  cc.  of  water  to  each  beaker  and 
stir  the  contents  for  15  minutes.  Allow  the  insoluble  residue  to  settle  for  3-5  min- 
utes, decant  the  Uquid  through  filters  into  beakers  and  add  25  cc.  of  water  to  each 
residue.  Stir  7-8  minutes  and,  after  allowing  to  settle,  decant  onto  the  same  filter. 
Continue  this  treatment,  using  25  cc.  of  water  each  time,  until  the  filtrates  measure 
about  230  cc.  each.  Allow  the  filters  to  drain  completely  between  extractions. 
Whenever  the  niajor  portion  of  the  residue  has  been  mechanically  transferred  to  the 
filter,  return  it  to  the  beaker.     After  the  last  extraction,  transfer  the  entire  con- 

271 


272  METHODS    OF   ANALYSIS  [Chap. 

tents  of  each  beaker  onto  the  filter  and,  when  drained,  wash  twice  with  small  quan- 
tities of  water.     Combine  the  2  extracts. 

(b)  Hot  water -aynmonium  sulphate  extract  of  blood. — Weigh  out  30-35  grams  of 
fresh  whole  blood  as  caught  from  the  animal  into  a  porcelain  mortar.  Grind  and 
transfer  to  a  400  cc.  beaker  with  hot  water.  Make  up  to  about  150  cc.  with  boil- 
ing water.  Place  over  a  flame,  gradually  bring  to  boiling,  with  constant  stirring, 
then  add  20  cc.  of  20%  ammonium  sulphate  solution  and  continue  boiling,  with 
constant  stirring,  for  about  10  minutes.  Decant  onto  an  18  cm.  filter  paper,  re- 
ceiving the  filtrate  in  an  800  cc.  beaker.  Transfer  the  coagulum  from  the  filter, 
along  with  that  remaining  in  the  beaker,  to  a  mortar.  Grind  to  a  smooth  paste 
and  transfer  to  a  beaker  with  boiling  35%  ammonium  sulphate  solution.  Make  up 
to  about  50  cc.  with  the  latter,  stir  for  8  minutes  and  again  filter.  Return  the 
coagulum  to  the  mortar  and  grind  again,  transferring  to  the  beaker  as  before  with 
boiling  31%  ammonium  sulphate  solution.  Repeat  this  process  of  8  minute  extrac- 
tions of  the  coagulum  in  33%  ammonium  sulphate  solution  and  filtration  as  directed 
above,  v/ithout  further  grinding,  until  the  filtrate  measures  about  450  cc.  Wash  out 
each  beaker  twice  with  8-10  cc.  of  hot  3§%  ammonium  sulphate  solution,  transferring 
the  coagulum  and  extract  to  the  filter.  Wash  the  coagulum  twice  with  boiUng33% 
ammonium  sulphate  solution  from  a  wash  bottle.  Always  allow  the  filter  to  drain 
well  between  additions  of  extract  or  wash  solutions. 

(C)  Hot  water-ammonhim  sulphate  extract  of  liver. — Weigh  by  difference  from  a 
closed  weighing  bottle  15-20  grams  of  finely  ground  liver  into  a  400  cc.  beaker.  Add 
a  few  cc.  of  cold  water  and  beat  up  with  a  stirring  rod  to  separate  the  particles  of 
tissue.  Add  enough  boiling  water  to  make  the  volume  about  150  cc,  place  over  a 
flame  and  bring  to  boiling.  Add  10  cc.  of  20%  ammonium  sulphate  solution  and 
continue  to  boil  for  10  minutes.  Allow  to  settle  for  a  moment  and  decant  the  boil- 
ing hot  liquid  onto  an  18  cm.  filter.  Add  50  cc.  of  boiling  water  and  stir  for  8  min- 
utes, without  further  heating,  and  decant  onto  the  filter  again.  Repeat  this  addi- 
tion of  50  cc.  of  hot  water,  stirring  and  decanting  8  times,  returning  the  coagulum 
to  the  beaker  as  soon  as  any  considerable  amount  collects  upon  the  filter.  With 
the  eighth  portion  of  water  transfer  the  entire  contents  of  the  beaker  onto  the  filter 
and  wash  tv.-ice  with  hot  water.  Always  allow  the  filter  to  drain  well  between 
additions  of  extract  or  wash  water. 

(d)  Hot  water-ammonium  sulphate  extract  of  brain. — Weigh  out  about  10  grams 
of  brain  into  a  250  cc.  beaker.  Add  a  few  cc.  of  water  and  work  up  the  brain  and 
water  with  a  glass  rod.  Make  up  to  about  100  cc.  with  boiling  water,  place  over  a 
flame,  and  gradually  bring  to  boiling,  with  constant  stirring.  While  boiling  vigor- 
ously fnot  before)  add  20  cc.  of  20%  ammonium  sulphate  solution,  boil  gently  for 
about  10  minutes,  allow  to  settle  for  a  moment  and  decant  slowly  onto  a  linen  filter 
containing  acid-washed,  glassmaker's  sand,  receiving  the  extract  in  an  800  cc. 
beaker.  Add  to  the  beaker  containing  the  coagulum  50  cc.  of  33%  ammonium 
sulphate  solution,  stir  1  minute,  keep  boiling  and  decant  the  liquid  onto  the  filter. 
Repeat  this  process  of  1  minute  extractions  of  the  coagulum  in  33%  ammonium 
sulphate  solution,  and  filtration  as  directed  above,  until  the  filtrate  measures  about 
450  cc.  Wash  out  the  beaker  twice  with  8-10  cc.  of  hot  3^%  ammonium  sulphate 
solution,  completing  the  transfer  of  the  coagulum  and  extract  to  the  sand,  and  v/ash 
the  coagulum  twice  with  the  wash  solution.  Always  allow  the  filter  to  drain  well 
between  additions  of  extract  or  wash  solution. 

In  making  extracts  of  brain,  give  careful  attention  to  the  handling  of  the  sample. 
The  coagulum  is  very  soft.  It  should  be  stirred  only  enough  to  keep  it  in  motion. 
If  handled  roughly  in  returning  from  the  sand  filter  to  the  beaker,  it  becomes  too 


XXI]  MEAT   AND    MEAT   PRODUCTS  273 

finely  divided  and  retains  a  great  deal  of  liquid.  To  prevent  the  extract  or  the 
coagulum  from  coming  into  contact  with  the  linen  before  passing  through  the  sand, 
pour  the  extract  slowly  into  a  slight  depression  in  the  center  of  the  sand  or,  better 
yet,  into  a  thip.  film  of  absorbent  cotton,  1^  inches  in  diameter,  laid  over  a  depres- 
sion in  the  sand.  The  coagulum  remains  on  the  cotton  and  its  return  to  the  beaker 
is  facihtated  thereby.  If  the  cotton  is  not  broken  up  by  needless  stirring,  it  can  be 
taken  out  of  the  beaker  with  a  glass  rod  and  returned  to  the  sand  each  time  a  partial 
extract  is  to  be  filtered.  Care  is  necessary  to  prevent  loss  through  bumping,  on 
account  of  sand  in  the  beakers  during  the  final  extractions.  P]ach  partial  extract 
should  be  boiling  hot  at  the  time  filtration  begins. 

7  DETERMINATION. 

To  the  extracts,  prepared  as  directed  in  6,  add  50  cc.  of  magnesia  mixture  [I,  4  (C)  J 
and  stir  thoroughly.  Allow  to  stand  15  minutes,  add  25  cc.  of  ammonium  hy- 
droxid  (sp.  gr.  0.90),  cover  and  allow  to  stand  3  days.  Filter  and  wash  the  pre- 
cipitate with  21%  ammonium  hydroxid.  Dissolve  the  precipitate  on  the  filter  paper 
and  that  remaining  in  the  beaker  in  nitric  acid  (1  to  1)  and  hot  water,  receiving 
the  solution  in  a  400  cc.  beaker.  Neutralize  with  ammonium  hydroxid,  make  sUghtly 
acid  with  nitric  acid,  add  5  grams  of  ammonium  nitrate  and  determine  phosphorus 
as  directed  under  I,  6. 

8  TOTAL  NITROGEN.— OFFICIAL. 

Proceed  as  directed  under  I,  18,  21  or  23,  using  about  2  grams  of  the  fresh 
sample.  In  the  Kjeldahl  and  Gunning  methods  digest  with  sulphuric  acid  for  at 
least  4  hours;  in  the  Kjeldahl-Gunning-Arnold  method  for  2  hours  after  the  mix- 
ture has  become  clear. 

9  SOLUBLE  AND  INSOLUBLE  NITROGEN.— TENTATIVE. 

Exhaust  7-25  grams  of  the  sample  depending  upon  the  water  content  in  the  fol- 
lowing manner:  Weigh  into  a  150  cc.  beaker,  add  5-10  cc.  of  cold  (15°C.)  ammonia- 
free  water  and  stir  to  a  homogeneous  paste.  Then  add  50  cc.  of  cold  water,  stir 
every  3  minutes  for  15  minutes,  let  stand  for  2-3  minutes  and  decant  the  liquid  upon 
a  quantitative  filter,  collecting  the  filtrate  in  a  500  cc.  graduated  flask.  Drain  the 
beaker,  pressing  out  the  liquid  from  the  meat  residue  by  the  aid  of  a  glass  rod. 
Add  to  the  residue  in  the  beaker  50  cc.  of  cold  water,  stir  for  5  minutes  and,  after 
standing  2-3  minutes,  decant  as  before.  If  a  considerable  portion  of  the  meat 
is  carried  over  onto  the  filter,  transfer  it  back  to  the  beaker  by  means  of  a  glass 
rod.  Repeat  the  extractions,  using  the  following  additional  amounts  of  cold  water: 
50,  50,  25,  25,  25  and  25  cc.  After  the  last  extraction  transfer  the  entire  insoluble 
portion  to  the  filter  and  wash  with  three  10  cc.  portions  of  water,  allowing  the  ma- 
terial to  drain  thoroughly  after  each  addition  of  water.  Dilute  to  the  mark,  mix 
thoroughly  and  determine  the  total  soluble  nitrogen  in  a  50  cc.  aliquot  as  directed 
under  I,  18,  21  or  23.  Subtract  the  percentage  of  soluble  nitrogen  from  the  per- 
centage of  total  nitrogen,  8,  to  obtain  the  percentage  of  insoluble  nitrogen.  To 
obtain  the  percentage  of  insoluble  protein  multiply  the  percentage  of  insoluble 
nitrogen  by  6.25. 

10  CONNECTIVE  TISSUE  NITROGEN.— TENTATIVE. 

Exhaust  10  grams  of  the  sample  with  cold  water  as  directed  under  9,  and  boil  the 
exhausted  residue  repeatedly  with  successive  portions  of  about  100  cc.  of  water 
until  the  total  hot  water  extract  amounts  to  approximately  1  liter.  Filter,  concen- 
trate and  determine  nitrogen  in  the  concentrated  extract.  Multiply  the  percentage 
of  nitrogen  so  obtained  by  5.55  to  obtain  the  percentage  of  nitrogenous  substances 
of  the  connective  tissue. 


274  METHODS    OF   ANALYSIS  [Chap. 

11  COAGULABLE  PROTEINS.— TENTATIVE. 

(For  uncooked  meat  only.) 
Measure  150  cc.  of  the  extract,  from  9,  into  a  250  cc.  beaker  and  evaporate  to  40 
cc.  on  a  steam  bath,  with  occasional  stirring.  Neutralize  to  phenolphthalein,  then 
add  1  cc.  of  N/1  acetic  acid  and  boil  gently  for  5  minutes.  The  coagulum  should 
separate  out  at  once,  leaving  a  clear  liquid.  Filter  on  quantitative  paper,  wash 
the  beaker  thoroughly  4  times  with  hot  water,  taking  special  care  to  clean  the  sides. 
Finally  wash  the  coagulum  on  the  filter  3  times,  dilute  the  combined  filtrate  and 
washings  to  a  definite  volume  and  reserve  for  the  determination  of  proteoses,  pep- 
tones and  gelatin,  12,  and  creatin,  16.  Transfer  the  coagulum  with  the  paper  to  a 
Kjeldahl  flask  and  remove,  with  concentrated  sulphuric  acid,  any  of  the  material 
adhering  to  the  beaker,  taking  the  usual  25  cc.  of  acid  in  5  cc.  portions  for  this  pur- 
pose, heating  the  acid  in  the  beaker  on  a  hot  plate  and  rubbing  with  a  glass  rod. 
Proceed  as  directed  under  8.  Multiply  the  percentage  of  nitrogen  obtained  by  6.25 
to  obtain  the  percentage  of  coagulable  proteins. 

PROTEOSES,  PEPTONES  AND  GELATIN. 

12  Modified  Tannin-Salt  Method^. — Tentative. 

Transfer  a  50  cc.  aliquot  of  the  filtrate,  obtained  in  11,  to  a  100  cc.  graduated 
flask,  add  15  grams  of  sodium  chlorid  and  10  cc.  of  cold  water,  shake  until  the  so- 
diimi  chlorid  has  dissolved  and  cool  to  12°C.  Add  30  cc.  of  24%  tannin  solution, 
cooled  to  12°C.,  fill  to  the  mark  with  water  previously  cooled  to  12°C.,  shake  and 
allow  the  mixture  to  stand  at  a  temperature  of  12°C.  for  12  hours  or  overnight. 
Filter  at  12°C.,  transfer  50  cc.  of  the  filtrate  to  a  Kjeldahl  flask  and  add  a  few  drops 
of  sulphuric  acid.  Place  the  flask  in  a  steam  bath,  connect  with  a  vacuum  pump 
and  evaporate  to  dryness.  Determine  nitrogen  in  the  residue  as  directed  in  I,  1 8, 
using  30  cc.  of  sulphuric  acid  for  the  digestion.  Conduct  a  blank  determination, 
using  the  same  amount  of  reagents,  and  correct  the  result  accordingly.  Mul- 
tiply the  corrected  result  by  2  and  deduct  the  amount  of  nitrogen  as  found  from  the 
nitrogen  determined  in  another  50  cc.  aliquot  of  the  filtrate  from  the  coagulable 
proteins  without  the  tannin-salt  treatment;  the  difference  multiplied  by  6.25  gives 
the  percentage  of  proteoses,  peptones  and  gelatin. 

13  MEAT  BASES.— TENTATIVE. 

Deduct  from  the  percentage  of  total  nitrogen,  8,  the  sum  of  the  percentages  of 
nitrogen,  obtained  in  the  determination  of  insoluble  proteins,  9,  coagulable  pro- 
teins, 11,  and  proteoses,  peptones  and  gelatin,  12,  to  obtain  the  percentage  of 
nitrogen  of  the  meat  bases.  Multiply  the  result  by  3.12  to  obtain  the  percentage  of 
meat  bases. 

AMMONIA. 
Folin  Aeration  Method^. — Tentative. 

14  APPARATUS. 

Employ  the  apparatus  illustrated  in  Fig.  9 ;  A  is  a  wash  bottle  one  fourth  full  of 
10%  sulphuric  acid;  5  is  a  tube  containing  the  sample;  C  is  a  rubber  disc  and  D  is  a 
5  cc.  bulb  to  prevent  spray  from  being  carried  over  into  the  tube  {E)  which  contains 
the  standard  acid;  F  is  a  safety  bottle. 


DETERMINATION. 


15 

Introduce  2-4  grams  of  the  finely  divided  meat  into  the  tube  {B)  and  add  20  cc. 
of  ammonia-free  water.     Place  a  measured  amount  of  N/25  or  N/50  sulphuric  or 


XXI] 


MEAT   AND    MEAT   PRODUCTS 


275 


hydrochloric  acid  in  tube  (E).  Then  add  1  cc.  of  saturated  potassium  oxalate  solu- 
tion to  the  sample  in  tube  (B),  introduce  a  few  drops  of  kerosene  and  finally  add 
just  sufficient  saturated  potassium  carbonate  solution  to  render  the  mixture  alkaline. 
Place  the  tubes  in  position  at  once,  pass  air  through  the  apparatus  and  titrate  the 
standard  acid  in  tube  (E)  at  hourly  intervals,  until  ammonia  ceases  to  be  given  off, 
using  methyl  red,  cochineal  or  congo  red  as  an  indicator.  If  preferred,  the  ammonia, 
collected  in  tube  (E),  may  also  be  determined  by  nesslerizing  as  directed  under 

IV,  11. 

1 3  CREATIN.— OFFICIAL. 

Evaporate  an  aliquot  or  the  remaining  portion  of  the  filtrate  and  washings  from 
the  coagulable  proteins,  1 1 ,  (a  portion  having  been  used  in  12),  to  5-10  cc,  transfer 
with  a  minimum  amount  of  hot  water  to  a  50  cc.  measuring  flask,  keeping  the  volume 
below  30  cc,  add  10  cc  of  2N  hydrochloric  acid  and  mix.     Hydrolyze  in  an  auto- 


ro  Socr/ojy 


FIG.  9.    APPARATUS  FOR  THE  FOLIN  AMMONIA  DETER  >IINATION. 


clave  at  117°-120°C.  for  20  minutes,  allow  the  flask  to  cool  somewhat,  remove  and 
chill  under  running  water.  Partially  neutralize  the  excess  of  acid  by  adding  7.5  cc. 
of  10%  sodium  hj^droxid  solution,  free  from  carbonates,  dilute  to  tlie  mark  and 
mix.  Make  a  preliminary  reading  on  20  cc.  to  ascertain  the  volume  to  use  to  obtain 
a  reading  of  approximately  S  mm.  and  transfer  to  a  500  cc.  graduated  flask.  Add 
10  cc  of  10%  sodium  hydroxid  solution  and  30  cc.  of  saturated  picric  acid  solution 
(1.2%).  Mix  and  rotate  for  30  seconds  and  let  stand  exactly  4\  minutes.  Dilute 
to  the  mark  at  once  with  water,  shake  thoroughly  and  read  in  a  Duboscq  colori- 
meter, comparing  the  color  with  N/2  potassium  dichromate  solution,  set  at  8  mm. 
If  the  reading  is  too  high  or  too  low  (above  9.5  or  below  7  mm.),  calculate  the 
quantity  necessary  to  obtain  a  reading  of  about  8  mm.  The  strength  of  the  dichro- 
mate solution  used  must  be  checked  against  a  standard  creatin  solution.  To  obtain 
the  values,  divide  81  by  the  reading  and  multiply  by  the  volume  factor  to  obtain  mg. 
of  creatinin;  this  value  multiplied  by  1.16  gives  creatin,  which,  divided  by  the  weight 
of  the  sample  and  multiplied  by  100  gives  the  per  cent  of  creatin. 


276  METHODS    OF   ANALYSIS  [Chap. 

The  use  of  Kober's  shade  and  the  painting  of  the  plunger,  as  suggested  for  this 
nephelometer,  assists  in  getting  a  sharper  end  point,  relieves  the  eye  strain  and 
may  be  employed  if  desired. 

Example. — 20  grams  of  meat  are  extracted  with  water  as  in  9,  and  the  extract 
diluted  to  500  cc. ;  150  cc.  of  this  latter  solution  (equivalent  to  6  grams  of  meat)  are 
treated  as  in  11.  The  filtrate  thus  obtained  is  then  evaporated  and  hydrolyzed  as 
above  and  then  diluted  to  50  cc. ;  25  cc.  of  this  last  solution  are  treated  with  sodium 
hydroxid  solution  and  picric  acid  solution  as  directed  above  and  diluted  to  500  cc. 
This  latter  solution  gives  a  reading  of  9  mm. 

-Q  X  ^  =  18  mg.  creatinin; 

0.018X1.16X100      -„,^ 
t; =  0.3o%  creatin. 


(In  chopped  meat,  sausage,  deviled  meat,  etc.) 

17  Qualitative  Test. — Tentative. 

Treat  5-6  grams  of  the  sample  with  boiling  water  for  2-3  minutes,  cool  the  mix- 
ture and  test  the  supernatant  liquid  with  iodin  solution.  In  using  this  test,  a  small 
amount  of  starch  may  be  present  as  the  result  of  the  use  of  spices.  If  a  marked 
reaction  is  given,  however,  it  may  be  concluded  that  starch  or  flour  has  been  added, 
and  a  quantitative  determination  maj^  be  made.  The  qualitative  method  may  be 
replaced  by  a  microscopic  examination,  which  discloses  not  only  the  presence  of 
added  starch,  but  also  the  variety  employed. 

18  Mayrhofer  Method,  Price  Modification*. — Tentative. 

Treat  in  a  200  cc.  beaker  10  grams  of  the  finely  divided  sample  with  75  cc.  of  an 
8%  solution  of  potassium  hydroxid  in  95%  alcohol  by  volume  and  heat  on  a  steam 
bath  until  all  the  meat  is  dissolved  (30-45  minutes).  Add  an  equal  volume  of  95% 
alcohol,  cool  and  allow  to  stand  for  at  least  an  hour.  Filter  by  suction  through  a 
thin  layer  of  asbestos  in  a  Gooch  crucible.  Wash  twice  with  warm  4%  potassium 
hydroxid  in  50%  alcohol  by  volume  and  then  twice  with  warm  50%  alcohol.  Dis- 
card the  washings.  Retain  as  much  of  the  precipitate  in  the  beaker  as  possible 
until  the  last  washing.  Place  the  crucible  with  contents  in  the  original  beaker, 
add  40  cc.  of  water  and  25  cc.  of  concentrated  sulphuric  acid.  Stir  during  the  addi- 
tion of  the  acid  and  make  sure  that  the  acid  comes  in  contact  with  all  the  precipi- 
tate. Allow  to  stand  about  5  minutes,  add  40  cc.  of  water  and  heat  just  to  boiling, 
stirring  constantly.  Transfer  the  solution  to  a  250  cc.  graduated  flask,  add  2  cc. 
of  20%  phosphotungstic  acid  solution,  allow  to  cool  to  room  temperature  and  make 
up  to  the  mark  with  water.  Filter  through  a  starch-free  filter  paper,  pipette  100 
cc.  of  the  filtrate  into  a  200  cc.  graduated  flask,  neutralize  with  sodium  hydroxid 
.solution,  make  up  to  volume  and  determine  the  dextrose  present  in  a  50  cc.  portion 
of  the  filtrate,  as  directed  under  VIII,  25,  titrating  the  cuprous  oxid  precipitate 
as  directed  under  VIII,  29.  The  weight  of  the  dextrose  multiplied  by  0.9  gives 
the  weight  of  the  starch. 

GLYCOGEN. 

19  Qualitative  Test^. — Tentative. 

Boil  50  grams  of  the  macerated  sample  with  50  cc.  of  water  for  15-30  minutes. 
Filter  the  broth  through  moistened  filter  paper  or  fine  linen.  To  a  portion  of  the 
filtrate  in  a  test  tube  add  a  few  drops  of  a  mixture  of  2  parts  of  iodin,  4  of  potassium 


XXI]  MEAT   AND    MEAT   PRODUCTS  277 

iodid  and  100  of  water.  In  the  presence  of  a  considerable  amount  of  glycogen  the 
latter  produces  a  dark  brown  color,  which  is  destroyed  by  heating  and  reappears 
on  cooling.  When  starch  is  present,  it  may  be  precipitated  by  treating  the  water 
extract  with  2  volumes  of  glacial  acetic  acid,  filtering  and  applying  the  test  for 
glycogen  to  the  filtrate. 

Trowbridge  and  Francis  Method". — Tentative. 

20  PREPARATIO>f   OF   SOLUTION. 

Weigh  out  by  difference  about  25  grams  of  the  finely  ground  and  thoroughly 
mixed  sample.  Place  in  a  400  cc.  beaker  and  mix  with  50  cc.  of  potassium  hydroxid 
solution  (1|  to  1),  free  from  carbonate.  Cover  the  beaker  with  a  watch  glass  and 
digest  on  the  water  bath  for  2  hours,  with  occasional  stirring.  At  the  end  of  the  2 
hours,  dilute  to  approximately  200  cc.  with  cold  water. 

Add  to  the  solution  an  equal  volume  of  95%  alcohol  by  volume,  cover  with  a 
watch  glass  and  set  aside  for  10-12  hours.  Decant  the  supernatant  liquid  through  a 
folded  18.5  cm.  filter,  allowing  the  glycogen  to  remain  in  the  beaker  and  wash  by 
decantation  with  66%  alcohol  (2  volumes  of  95%  alcohol  to  1  of  water)  until  the 
glycogen  is  white,  or  nearly  so.  Usually  about  4  washings  are  required.  Transfer 
the  washed  precipitate  from  the  beaker  to  the  filter  and  wash  2-3  times  with  66% 
alcohol.  The  solution  filters  slowly  and  the  funnel  should  be  covered  with  a  watch 
glass  to  prevent  excessive  evaporation.  The  albuminous  substance  present  retards 
the  filtration  if  permitted  to  dry  on  the  paper.  If  the  washing  by  decantation  is  not 
made  nearly  complete,  it  will  be  difficult  to  obtain  the  glycogen  free  from  the  coloring 
matter. 

After  the  washing  is  completed,  close  the  bottom  of  the  funnel  by  a  piece  of  rub- 
ber tubing  and  a  pinch-cock.  Fill  the  funnel  with  warm  water,  cover  with  the  watch 
glass  and  let  stand  2-3  hours,  or  overnight.  Open  the  pinch-cock  and  allow  all 
of  the  solution  to  pass  through  the  filter  into  a  beaker.  Close  the  funnel  with  the 
pinch-cock  and  fill  with  warm  water  as  before.  Allow  this  water  to  remain  in  the 
funnel  for  an  hour  and  then  filter  as  before.  At  first  the  glycogen  solution  appears 
quite  turbid.  This  washing  with  warm  water  should  be  continued  until  the  filtrate 
becomes  perfectly  clear.  To  the  solution  of  glycogen  in  water,  add  double  its 
volume  of  95%  alcohol  by  volume  and  let  stand  overnight  to  complete  the  repre- 
cipitation  of  the  glycogen.     Filter  and  wash  as  before  with  66%  alcohol. 

21  DETERMINATION. 

If  desired,  the  last  filtration  may  be  made  through  a  tared  Gooch  crucible  and  the 
weight  of  glycogen  determined  after  drying  to  constant  weight.  This  gives  results 
that  are  approximately  correct.  More  satisfactory  results  are  obtained  by  hydrolyz- 
ing  the  glycogen  with  dilute  hydrochloric  acid  and  determining  the  resultant  dex- 
trose. Dissolve  the  glycogen  on  the  filter  in  warm  water  as  directed  above,  collect- 
ing the  filtrate  and  washings  in  a  300  cc.  graduated  flask  and  keeping  the  volume 
within  225  cc.  Add  12.5  cc.  of  hydrochloric  acid  (sp.  gr.  1.19)  to  the  combined  fil- 
trate and  washings,  mix  and  place  in  a  boiling  water  bath  for  3  hours.  Cool,  neu- 
tralize with  sodium  hydroxid  solution,  cool  again,  make  up  to  volume  with  water 
and  determine  dextrose  in  an  aliquot  of  the  solution  as  directed  under  VIII,  54, 
determining  the  reduced  copper  as  directed  under  VIII,  29.  Multiply  the  cor- 
responding weight  of  dextro'se  by  0.9  to  obtain  its  equivalent  of  glycogen  and  correct 
this  result  for  dilution  to  obtain  the  per  cent  of  glycogen  in  the  sample. 


278  METHODS    OF   ANALYSIS  [Chap. 

SUGAR^.-TENTATIVE. 

22  REAGENTS. 

(a)  Mercuric  nitrate  solution. — Warm  220  grams  of  yellow  mercuric  oxid  with 
300  cc.  of  water  and  treat  with  small  portions  of  nitric  acid,  stirring  until  dissolved. 
Make  up  to  1  liter  and  filter. 

(b)  Phosphotungstic  acid  solution. — Prepare  a  20%  solution  of  phosphotungstic 
acid  in  2.5%  hydrochloric  acid. 

23  DETERMINATION. 

Boil  100  grams  of  the  sample  with  about  350  cc.  of  water  for  about  20  minutes, 
cool,  add  an  excess  (10-30  cc.)  of  the  mercuric  nitrate  solution,  nearly  neutralize 
with  sodium  hydroxid  solution  and  make  up  to  500  cc,  exclusive  of  fat.  Mix  thor- 
oughly, allow  the  mixture  to  settle  and  decant  the  clear  liquid  through  a  large,  dry, 
folded  filter.  To  an  aliquot  of  the  filtrate  add  1-2  cc.  of  concentrated  hydrochloric 
acid  for  each  100  cc,  heat  to  boiling  and  saturate  thoroughly  with  a  rapid  current 
of  hydrogen  sulphid.  Remove  the  excess  of  hydrogen  sulphid  by  means  of  a  cur- 
rent of  air,  cool,  make  up  to  a  definite  volume  with  water  and  filter.  To  an  aliquot 
of  the  filtrate  add  an  excess  of  the  phosphotungstic  acid  solution,  noting  the  in- 
crease in  volume  of  the  solution  caused  by  this  addition  and  place  in  an  ice  box 
for  several  hours  or  overnight.  Filter,  introduce  50  cc  of  the  filtrate  into  a  400  cc. 
beaker,  neutralize  with  concentrated  sodium  hydroxid  solution,  add  50  cc.  of  Soxh- 
let's  solution  [VIII,  19],  heat  so  that  boiling  begins  in  4  minutes,  boil  2  minutes  and 
filter  through  an  alundum  crucible  of  suitable  porosity,  using  very  gentle  suction. 
If  the  filtrate  is  green  or  yellow,  refilter  through  the  same  crucible  until  the  fil- 
trate is  clear  blue.  Wash  the  precipitate  with  a  very  small  amount  of  5%  sodium 
hydroxid  solution,  refiltering  the  washings  if  they  are  turbid.  Dissolve  the  precipi- 
tated cuprous  oxid  in  nitric  acid  (1  to  1)  and  determine  copper  as  directed  under 
VIII,  29.  Find  the  corresponding  amount  of  dextrose  or  invert  sugar  from  VIII, 
27,  and  calculate  the  per  cent  in  the  original  sample  by  proper  correction  for  the 
various  aliquots  taken  in  the  determination.  To  convert  invert  sugar  to  sucrose 
multiply  by  the  factor  0.95. 

NITRATES. 
Sclildsing-W agner  Method^. — Tentative. 

2A  REAGENT. 

Ferrous  chlorid  solution. — Dissolve  nails  or  other  small  pieces  of  iron  in  concen- 
trated hydrochloric  acid,  keeping  an  excess  of  iron  present  until  the  evolution  of  gas 
ceases.  Keep  the  solution  in  50  cc.  glass-stoppered  bottles  entirely  filled.  Employ 
only  freshly  opened  bottles  of  the  reagent  for  the  determination. 

25  APPARATUS. 

Provide  a  250  cc.  flask  with  a  2-holed  rubber  stopper.  Through  one  of  the  holes 
pass  the  stem  of  a  funnel  having  a  glass  stop-cock,  and  into  the  other  fit  a  delivery 
tube  leading  downward  at  an  angle  from  the  flask  to  a  trough  containing  water. 
Terminate  the  upper  end  of  the  delivery  tube  just  below  the  rubber  stopper  in 
the  flask  and  place  the  lower  end  under  the  surface  of  the  water  in  the  trough,  the 
exit  being  immediately  beneath  the  mouth  of  an  inverted  measuring  tube,  filled 
with  40%  potassium  hydroxid  solution.  Cover  the  trough  end  of  the  delivery  tube 
with  a  piece  of  rubber  tubing.  Midway  on  the  delivery  tube  between  the  flask  and 
the  measuring  tube  place  a  short  length  of  rubber  tubing  and  a  pinch-cock. 


XXI]  MEAT   AND    MEAT   PRODUCTS  279 

26  DETERMINATION. 

Extract  100  grams  of  finely  ground  meat  by  boiling  repeatedly  with  successive 
small  portions  of  water,  decanting  the  extracts  through  a  muslin  or  paper  filter 
into  a  casserole,  and  concentrate  the  combined  extracts  to  a  volume  of  about  50  cc. 

Introduce  50  cc.  of  the  ferrous  chlorid  solution  and  50  cc.  of  10%  hydrochloric  acid 
into  the  flask,  close  the  stop-cock  of  the  funnel,  open  the  pinch-cock  on  the  deUvery 
tube,  move  the  end  of  the  latter  so  that  escaping  air  will  not  pass  into  the  measuring 
tube,  and  boil  the  contents  of  the  flask  until  the  air  is  expelled,  as  indicated  by  a 
slight  pressure  against  the  fingers  when  the  rubber  tubing  is  compressed  after  mo- 
mentary removal  of  the  flame.  Now  close  the  delivery  tube  with  the  pinch-cock 
and  place  the  exit  end  beneath  the  measuring  tube.  Introduce  the  concentrated 
extract  of  the  sample  into  the  flask,  a  little  at  a  time,  through  the  funnel  tube, 
opening  the  pinch-cock  on  the  delivery  tube  and  boiling  the  contents  of  the  flask 
at  intervals  to  force  the  nitric  oxid  gas  into  the  measuring  tube.  Finally  rinse  the 
casserole  and  the  funnel  tube  with  a  little  boiled  water,  add  the  rinsings  to  the  con- 
tents of  the  evolution  flask  in  the  manner  just  described  and  boil  until  nitric  oxid 
no  longer  passes  over  into  the  measuring  tube.  Calculate  the  volume  of  nitric 
oxid  at  0°C.  and  760  mm.  pressure.  One  cc.  of  nitric  oxid  at  0°C.  and  760  mm. 
pressure  is  equivalent  to  0.004512  gram  of  potassium  nitrate. 

Phenoldisulphonic  Acid  Method^. — Tentative. 

27  REAGENTS. 

(a)  Phenoldisulphonic  acid  solution. — Heat  6  grams  of  phenol  with  37  cc.  of  con- 
centrated sulphuric  acid  on  a  water  bath,  cool  and  add  3  cc.  of  water. 

(b)  Standard  comparison  solution. — Dissolve  1  gram  of  pure,  dry  potassium  ni- 
trate in  water  and  dilute  to  1  liter.  Evaporate  10  cc.  of  this  solution  to  dryness 
on  a  steam  bath,  add  2  cc.  of  the  phenoldisulphonic  acid  solution,  mix  quickly  and 
thoroughly  by  means  of  a  glass  rod,  heat  for  about  a  minute  in  a  steam  bath  and 
dilute  to  100  cc.  One  cc.  of  this  solution  is  equivalent  to  0.1  mg.  of  potassium  ni- 
trate. Prepare  a  series  of  standard  comparison  tubes  by  introducing  amounts 
ranging  from  1-20  cc.  of  this  solution  (0.1-2.0  mg.  of  potassium  nitrate)  into  50  cc. 
Nessler  tubes,  adding  5  cc.  of  strong  ammonium  hydroxid  to  each  and  diluting  to 
50  cc.  These  standard  tubes  are  permanent  for  several  weeks  if  kept  tightly 
stoppered. 

28  DETERMINATION. 

Weigh  1  gram  of  the  sample  into  a  100  cc.  flask,  add  20-30  cc.  of  water  and  heat 
on  a  steam  bath  for  15  minutes,  shaking  occasionally.  Add  3  cc.  of  saturated  silver 
sulphate  solution  for  each  per  cent  of  sodium  chlorid  present,  then  10  cc.  of  basic 
lead  acetate  solution  and  5  cc.  of  alumina  cream,  shaking  after  each  addition. 
Make  up  to  the  mark  with  water,  shake  and  filter  through  a  folded  filter,  returning 
the  filtrate  to  the  filter  until  it  runs  through  clear.  Evaporate  25  cc.  of  the  filtrate 
to  dryness,  add  1  cc.  of  the  phenoldisulphonic  acid  solution,  mix  quickly  and  thor- 
oughly by  means  of  a  glass  rod,  add  1  cc.  of  water  and  3  or  4  drops  of  concentrated 
Bulphuric  acid  and  heat  on  a  steam  bath  for  2-3  minutes,  being  careful  not  to  char 
the  material.  Then  add  about  25  cc.  of  water  and  an  excess  of  ammonium  hydroxid, 
transfer  to  a  100  cc.  graduated  flask,  add  1-2  cc.  of  alumina  cream  if  not  perfectly 
clear,  dilute  to  the  mark  with  water  and  filter.  Fill  a  50  cc.  Nessler  tube  to  the 
mark  with  the  filtrate  and  determine  the  amount  of  potassium  nitrate  present  in 


I 


280  METHODS    OF   ANALYSIS  [Chap. 

the  sample  by  comparison  with  the  standard  comparison  tubes.  If  the  solution  is 
too  dark  for  comparison  with  the  standards,  dilute  with  water  and  correct  the 
result  accordingly. 

29  PRESERVATIVES.— TENTATIVE. 
Proceed  as  directed  under  X. 

30  METALS.-TENTATIVE. 
Proceed  as  directed  under  XII. 

31  COLORING  MATTERS.-TENTATIVE. 
Proceed  as  directed  under  XI. 

MEAT  EXTRACTS  AND  SIMILAR  PRODUCTS. 

32  PREPARATION  OF  SAMPLE.-TENTATIVE. 

Remove  liquid  and  semi-liquid  meat  extracts  and  similar  preparations  from  the 
container  and  mix  thoroughly  before  sampling.  A  little  heating  expedites  the 
mixing  of  pasty  extracts.  In  many  liquid  preparations  a  sediment  forms  which 
should  be  carefully  removed  from  the  bottom  of  the  container  and  included  in  the 
sample.     If  the  sample  is  in  the  form  of  cubes,  grind  10-12  of  the  cubes  in  a  mortar. 

33  MOISTURE.-TENTATIVE. 

Proceed  ae  directed  under  VIII,  2,  employing  about  2  grams  of  powdered  prepa- 
rations, about  3  grams  of  pasty  preparations,  or  5-10  grams  of  liquid  extracts, 
according  to  the  solid  content.  Dry  the  powdered  preparations  directly  without 
admixture.  Dissolve  the  pasty  preparations  in  water  and  dry  with  sufficient  ignited 
sand,  asbestos  or  pmnice  stone  to  absorb  the  solution.  When  glycerol  is  present, 
proceed  as  directed  under  VIII,  3. 

34  ASH.-OFFICIAL. 

Proceed  as  directed  under  VIII,  4.  Add  sufficient  water  tt)  pasty  preparations 
to  effect  solution  and  evaporate  to  dryness  in  order  that  the  solids  may  be  distrib- 
uted evenly  over  the  bottom  of  the  dish. 

35  TOTAL  PHOSPHORUS.— TENTATIVE. 

Proceed  as  directed  under  5. 

30  CHLORIN.— TENTATIVE. 

Dissolve  about  1  gram  of  the  sample,  prepared  as  directed  in  32,  in  20  cc.  of  5% 
sodium  carbonate  solution  and  proceed  as  directed  under  III,  18. 

37  FAT.— TENTATIVE. 

Transfer  the  residue  from  the  determination  of  moisture  to  a  continuous  extrac- 
tion apparatus  and  proceed  as  directed  under  VIII,  10. 

38  TOTAL  NITROGEN.— OFFICIAL. 

Proceed  as  directed  under  I,  18,  21  or  23. 


XXI]  MEAT   AND    MEAT    PRODUCTS  281 

39  INSOLUBLE  PROTEIN' ".-TENTATIVE. 

Dissolve  5  grams  of  powdered  preparations,  8-10  grams  of  pasty  extracts,  or  20- 
25  grams  of  fluid  extracts,  in  cold  water.  Filter  and  wash  with  cold  water.  Trans- 
fer the  filter  paper  and  contents  to  a  Kjeldahl  flask  and  determine  nitrogen  as  di- 
rected under  1, 1 8,  21  or  23.  However,  i  f  a  large  amount  of  insoluble  matter  is  pres- 
ent, transfer  the  weighed  sample  to  a  graduated  flask,  make  up  to  a  definite  volume, 
shake  thoroughly,  filter  through  a  folded  filter  and  determine  nitrogen  in  an  aliquot 
of  the  filtrate.  Deduct  the  percentage  of  nitrogen  in  the  total  filtrate  from  the 
percentage  of  total  nitrogen,  38,  to  obtain  the  percentage  of  nitrogen  in  the  insol- 
uble protein.  Multiply  this  percentage  of  nitrogen  by  6.25  to  obtain  the  percentage, 
of  insoluble  protein. 

40  COAGULABLE  PROTEIN.-TENTATIVE. 

Prepare  a  solution  of  the  sample  as  directed  in  39.  Employ  as  large  an  aliquot 
of  the  filtrate  as  practicable  or  an  aliquot  of  the  filtrate  from  the  insoluble  protein,  39, 
and  neutralize  to  phenolphthalein  by  the  addition  of  acetic  acid  or  sodium  hydroxid, 
whichever  may  be  necessary,  add  1  cc.  of  N/1  acetic  acid,  boil  for  2-3  minutes, 
cool  to  room  temperature,  dilute  to  500  cc.  and  pass  through  a  folded  filter. 

Determine  nitrogen  in  50  cc.  of  the  filtrate  as  directed  under  I,  18,  21  or  23. 
Ten  times  the  percentage  of  nitrogen  so  obtained  subtracted  from  the  percentage 
of  soluble  nitrogen  (total  nitrogen  minus  the  percentage  of  nitrogen  occurring  as 
insoluble  protein)  gives  the  percentage  of  nitrogen  present  as  coagulable  protein. 
Multiply  this  figure  by  6.25  to  obtain  the  percentage  of  coagulable  protein  in  the 
sample. 

41  AMMONIA.-TENTATIVE. 

Mix  1  gram  of  meat  extract  with  2  cc.  of  N/1  hydrochloric  acid,  wash  into  a  Folin 
apparatus  with  about  5  cc.  of  water  and  proceed  as  directed  under  15. 

42  PROTEOSES  AND  GELATIN".— TENTATIVE. 

Evaporate  the  filtrate  from  40  to  a  small  volume  and  saturate  with  zinc  sulphate 
(about  85  grams  to  50  cc,  avoiding  such  an  excess  as  would  later  cause  bumping). 
Let  stand  several  hours,  filter  and  wash  the  precipitate  with  saturated  zinc  sul- 
phate solution,  place  the  filter  and  precipitate  in  a  Kjeldahl  flask  and  determine  ni- 
trogen as  directed  under  I,  1 8,  21  or  23.  Or,  if  the  precipitate  is  voluminous,  which 
rarely  happens,  make  up  to  a  definite  volume  with  saturated  zinc  sulphate  solution, 
filter  and  determine  the  nitrogen  in  an  aliquot  of  the  filtrate,  as  directed  under  I, 
18,  21  or  23,  and  subtract  the  nitrogen  thus  obtained  from  the  nitrogen  in  the 
filtrate  from  the  coagulable  protein  to  obtain  the  nitrogen  of  the  precipitated 
protein  (proteoses  and  gelatin). 

43  GELATIN.— TENTATIVE. 

Prepare  a  50%  solution  of  the  sample,  using  hot  water.  Allow  to  cool  and  place 
in  an  ice  box  for  2  hours.     If  gelatin  is  present,  the  solution  will  set. 

The  ratio  of  total  creatinin  to  total  nitrogen  in  a  normal  meat  extract  (1  :  1.5) 
assists  in  determining  the  presence  of  gelatin  or  gelatin  derivatives.  The  ratio  is 
decreased  when  gelatin  or  gelatin  derivatives  are  present  in  any  considerable 
amount. 


282 


METHODS    OF   ANALYSIS 


[Chap. 


AMINO  NITROGEN. 
Van  Slyke  Method^''. —  Tentative. 

44  REAGENTS. 

(a)  Alkaline  ■permanganate  solution. — Dissolve  50  grams  of  potassium  permanga- 
nate and  25  grams  of  potassium  hj'droxid  in  sufficient  water  to  make  1  liter. 

(b)  Sodium  nitrite  solution. — Dissolve  30   grams  of  sodium  nitrite  in  sufficient 
water  to  make  100  cc. 

(C)  Glacial  acetic  acid. 


FIG.  10.    VAN  SLYKE  APPARATUS  FOR  THE  DETERMINATION  OF  AMINO  NITROGEN. 

{By  courtesy  of  the  Journal  of  Biological  Chemistry.) 


45  APPARATUS. 

Employ  the  apparatus  shown  in  Figs.  10  and  11,  the  former  illustrating  the  man- 
ner in  which  the  entire  apparatus  is  arranged  and  the  latter  showing  the  details 


XXI] 


MEAT   AND    MEAT   PRODUCTS 


283 


of  the  deaminizing  bulb  and  connections, 
the  alkaline  permanganate  solution. 


The  Hempel  gas  pipette  is  filled  with 


46  DETERMINATION. 

Fill  with  water  the  burette  (F),  the  capillary  tube  leading  to  the  Hempel  pipette 
and  also  the  other  capillary  as  far  as  c.  Introduce  into  A  sufficient  glacial  acetic 
acid  to  fill  one  fifth  of  D,  the  tube  (A)  being  etched  with  a  mark  to  measure  this 


P'pette 


FIG.  11.    DETAILS  OF  THE  DEAMINIZING  BULB  AND  CONNECTION. 

(By  courtesy  of  the  Journal  of  Biological  Chemistry.) 


amount.  Allow  the  acid  to  run  into  D,  the  cock  c  being  turned  so  as  to  allow  the 
air  to  escape  from  D.  Pour  the  sodium  nitrite  solution  into  A  until  D  is  full  of  solu- 
tion and  enough  e.xcess  is  present  to  rise  a  little  above  the  cock  into  A.  A  is  also 
marked  for  measuring  off  this  amount.  Then  close  the  gas  exit  from  D  at  c,  and, 
a  being  open,  shake  D  for  a  few  seconds  until  the  liquid  is  forced  down  to  the  20 
cc.  mark  in  D.  Then  close  a,  open  c  and  shake  the  apparatus  rapidly  with  the 
motor  for  2  minutes,  these  operations  being  for  the  purpose  of  expelling  all  the  air 
from  D.    Then  turn  c  and  /  so  that  D  and  F  are  connected. 


284  METHODS   OF  ANALYSIS  [Chap. 

Measure  off  in  B  10  c,-.  or  less,  as  the  case  may  be,  of  the  solution  of  the  sample 
containing  not  more  than  20  mg.  of  amino  nitrogen  (about  1-2  grams  of  the  sample) 
and  allow  it  to  run  into  D.  Connect  D  with  the  motor  as  shown  in  Fig.  10  and 
shake  for  5  minutes. 

If  the  solution  of  the  sample  is  viscous  and  threatens  to  foam  over,  rinse  out  B, 
and  then  through  it  introduce  a  little  caprylic  alcohol  into  D,  or,  if  it  is  known 
beforehand  that  the  sample  will  cause  excessive  foaming,  introduce  a  little  caprylic 
alcohol  into  D  through  B,  rinsing  B  with  alcohol  and  ether  or  drying  with  a  roll  of 
filter  paper  before  adding  the  solution  of  the  sample. 

During  the  shaking  there  is  an  evolution  of  nitrogen  mixed  with  nitric  oxid,the 
gases  being  collected  in  F:  Force  all  the  gas  in  D  into  F  by  opening  a  and  filling 
D  with  liquid  from  A.  Connect  F  with  the  Hempel  pipette  and  force  the  gas  into 
the  latter  by  means  of  the  leveling  bulb,  allowing  the  cock  a  to  remain  open  during 
this  and  the  succeeding  operation  in  order  to  permit  displacement  of  the  liquid  in 
D  by  the  nitric  oxid  formed  in  the  interval.  Connect  the  driving  rod  with  the 
pipette  by  lifting  the  hook  from  the  shoulder  of  D  and  placing  the  other  hook,  on 
the  opposite  side  of  the  driving  rod,  over  the  horizontal  lower  tube  of  the  pipette. 
Shake  the  pipette  rather  slowly  for  a  minute  which,  with  any  but  almost  completely 
exhausted  permanganate  solutions,  completes  the  absorption  of  nitric  oxid.  Then 
return  the  gas  to  the  burette,  adjust  the  level  with  the  leveling  bulb  and  note  the 
volume  of  nitrogen,  the  temperature  and  barometric  pressure,  and  calculate  the 
volume  of  nitrogen  under  standard  conditions  of  temperature  and  pressure.  Ob- 
tain the  corresponding  weight  of  nitrogen,  divide  the  latter  by  2,  and  from  the 
quotient  calculate  the  apparent  per  cent  of  amino  nitrogen  in  the  sample.  Cor- 
rect the  result  for  a  blank  test  performed  as  above,  using  10  cc.  of  water  instead  of 
the  solution  of  the  sample.  The  amount  of  gas  obtained  in  the  blank  is  usually 
0.3-0.4  cc,  and  nitrite  solutions  giving  a  much  larger  correction  should  be 
rejected. 

In  the  case  of  beef  extracts  and  similar  preparations  5  minutes  is  sufficient  time 
to  allow  for  the  completion  of  the  reaction  in  D.  In  general  the  same  time  serves 
for  the  decomposition  of  alpha-amino  acids  but  with  ammonia,  methylamin  and 
most  amines  other  than  alpha-amines  1-1|  hours  should  be  allowed.  For  determi- 
nations on  such  substances  mix  the  solution  of  the  sample  with  the  reagents  as  de- 
scribed above,  allow  the  mixture  to  stand  in  the  apparatus  till  the  end  of  the  re- 
quired time,  and  conclude  the  reaction  by  shaking  the  apparatus  with  the  motor  for 
2-3  minutes.     Continue  the  determination  from  this  point  as  directed  above. 

47  ACID  ALCOHOL-SOLUBLE  NITROGENi^.— TENTATIVE. 

Transfer  10  cc.  of  an  aqueous  solution  of  the  sample  (10  grams  of  the  sample 
dissolved  in  sufficient  water  to  make  100  cc.)  or,  if  the  sample  is  insoluble  in  water, 
1  gram  of  the  sample  and  10  cc.  of  water,  to  a  200  cc.  glass-stoppered  measuring 
cylinder,  add  1.2  cc.  of  12%  hydrochloric  acid,  mix  and  add  absolute  alcohol  to  the 
200  cc.  mark.  Mix  thoroughly  and  set  aside  for  several  hours.  If  necessary  make 
up  to  volume,  filter,  transfer  100  cc.  of  the  filtrate  to  a  Kjeldahl  flask,  evaporate  the 
alcohol  on  a  water  bath  and  determine  nitrogen  in  the  residue  as  directed  under  I, 

18,  21  or  23. 

48  CREATIN.-OFFICIAL. 

Dissolve  about  7  grams  of  the  sample  in  cold  (20°C.)  ammonia-free  water  in  a 
150  cc.  beaker,  transfer  the  solution  to  a  250  cc.  measuring  flask,  dilute  to  the  mark 


XXI]  MEAT   AND    MEAT    PRODUCTS  285 

and  mix  thoroughly.  Transfer  a  20  cc.  aliquot  of  this  solution  to  a  50  cc.  meas- 
uring flask  and  proceed  as  directed  under  16.  Subtract  from  the  combined  creati- 
nin  value  the  equivalent  of  the  pre-formed  creatinin,  49,  and  multiply  the  difference 
by  1.16  to  convert  into  creatin.     Express  the  result  as  per  cent  of  creatin. 

49  CREATININ.-OFFICIAL. 

For  creatinin  in  beef  extract  measure  about  5  cc.  of  the  solution  employed  in  48 
into  a  500  cc.  measuring  flask,  add  10  cc.  of  10%  sodium  hydroxid  solution  and  30 
cc.  of  the  saturated  picric  acid  solution  (1.2%),  mix  and  rotate  for  30  seconds.  Allow- 
to  stand  exactly  4^  minutes,  then  dilute  to  the  mark  at  once  with  water.  Shake 
thoroughly  and  read  the  depth  of  color  after  standing.  If  the  reading  is  less  than 
7  or  over  9.5  mm.,  repeat,  calculating  the  quantity  of  solution  necessary  to  obtain  a 
reading  of  about  8  mm.  Express  the  result  as  per  cent  of  creatinin,  making  the 
calculations  as  indicated  under  16. 

GLYCEROL. 

50  Cook  Method^*.— Tentative. 

Weigh  2  grams  of  a  solid  or  5  grams  of  a  liquid  preparation  in  a  small  lead  dish  or 
Hofmeister  Schalchen  containing  20  grams  of  ignited  sand.  Transfer  the  dish  and 
its  contents  to  a  mortar  containing  more  ignited  sand  and  several  grams  of  anhydrous 
sodium  sulphate  and  mix  thoroughly.  Transfer  the  mixture,  including  the  dish, 
to  a  Soxhlet  apparatus  which  has  a  piece  of  cotton  placed  in  the  side  arm  to  prevent 
solid  particles  from  being  siphoned  over.  Extract  the  entire  mass  with  redistilled 
anhydrous  acetone  for  10  hours.  Distil  the  acetone  from  the  extract,  carefully  re- 
moving the  last  trace  by  means  of  a  vacuum  pump.  Take  up  the  residue  in  water, 
add  5  cc.  of  10%  silver  nitrate  solution,  make  up  to  a  volume  of  100  cc,  shake,  allow 
to  stand  overnight,  filter  and  determine  glycerol  in  an  aliquot  of  the  filtrate  as  di- 
rected under  XIX,  6,  beginning  at  the  point  "Add  *  *  *  30  cc.  of  the  strong 
potassium  dichromate  solution".  With  solid  meat  and  yeast  extracts  a  blank  of 
0.5-1.0  %  is  obtained  in  most  cases. 

51  SUGAR.-TENTATIVE. 

Heat  20  grams  of  the  sample  with  about  200  cc.  of  water  on  a  steam  bath  until  all 
soluble  substances  have  gone  into  solution,  cool  and  proceed  from  this  point  as 
directed  under  23.  Reducing  sugar  up  to  0.5%  may  be  present  as  a  natural  con- 
stituent of  meat  extracts. 

52  PRESERVAXrVES.-TENTATIVE. 
Proceed  as  directed  under  X. 

53  METALS.— TENTATIVE. 
Proceed  as  directed  under  XII. 

54  NITRATES.-TENTATIVE. 
Proceed  as  directed  under  26  or  28. 


286  METHODS    OF  ANALYSIS 

BIBLIOGRAPHY. 

>  J.  Assoc.  Official  Agri.  Chemists,  1915,  1:  230. 

2  J.  Am.  Chem.  Soc,  1906,  28:  1485. 

3  J.  Assoc.  Official  Agri.  Chemists,  1915,  1:  174. 

*  U.  S.  Bur.  Chem.  Bull.  162,  p.  97. 

5  Abs.  Z.  Nahr.  Hyg.  Waar.,  1896,  10:  173. 

'  J.  Ind.  Eng.  Chem.,  1910,  2:  21,  215. 

^  J.  Assoc.  Official  Agri.  Chemists,  1915,  1:  177. 

*  Tiemann.  Anleitung  zur  Untersuchung  von  Wasser.  1870,  p.  56;  Wiley.  Prin- 
ciples and  Practice  of  Agricultural  Analysis.  2nd  ed.,  1906-14,  2:397;  U.  S.  Bur. 
Chem.  Bull.  13  (X),  p.  1403. 

8  U.  S.  Bur.  Chem.  Bull.  13  (X),  p.  1405. 

1"  Allen.     Commercial  Organic  Analysis.  4th  ed.,  1909-14,  8:  407. 

"  Z.  anal.  Chem.,  1895,  34:  562;  U.  S.  Bur.  Chem.  Bull.  54. 

'*  J.  Biol.  Chem.,  1911,  9:  185;  1912,  12:  275;  1913,  16:  121;  1915,  23:  407. 

"  J.  Am.  Chem.  Soc,  1914,  36:  1551. 

"  J.  Assoc.  Official  Agri.  Chemists,  1915,  1:  279. 


XXII.     DAIRY  PRODUCTS. 

MILK. 

1  SOLIDS.— OFFICIAL. 

Heat  3-5  grams  of  the  milk  at  the  temperature  of  boiling  water  until  it  ceases 
to  lose  weight,  using  a  tared,  flat-bottomed  dish  of  not  less  than  5  cm.  diameter. 
If  desired,  previously  place  15-20  grams  of  pure,  dry  sand  in  the  dish.  Cool  in  a 
desiccator  and  weigh  rapidly  to  avoid  absorption  of  h3'groscopic  moisture. 

2  ASH.— OFFICLAL. 

Weigh  about  20  grams  of  the  milk  in  a  tared  dish,  add  6  cc.  of  nitric  acid,  evap- 
orate to  dryness  and  ignite  at  a  temperature  just  below  redness  until  the  ash  is  free 
from  carbon. 

3  TOTAL  NITROGEN.-OFFICL/^L. 

Place  about  5  grams  of  the  milk  in  a  Kjeldahl  digestion  flask  and  proceed,  without 
evaporation,  as  directed  under  I,  18,  21  or  23.  Multiply  the  percentage  of  nitro- 
gen by  6.38  to  obtain  the  equivalent  percentage  of  nitrogen  compounds. 

CASEIN. 

(This  determination  should  be  made  while  the  milk  is  fresh,  or  nearly  so. 

When  it  is  not  practicable  to  make  this  determination  within 

24  hours,    add   1    part   of  formaldehyde   to  2500 

parts  of  milk  and  keep  in  a  cool  place.) 

4  Method  I.— Official. 

Place  10  grams  of  the  milk  in  a  beaker  with  90  cc.  of  water  at  40°-42°C.  and  add 
at  once  1.5  cc.  of  10%  acetic  acid.  Stir  and  let  stand  3-5  minutes.  Then  decant 
on  a  filter,  wash  by  decantation  2-3  times  with  cold  water  and  transfer  the  precipi- 
tate to  the  filter.  Wash  once  or  twice  on  the  filter.  The  filtrate  should  be  clear, 
or  very  nearly  so.  If  the  first  portions  of  the  filtrate  are  not  clear,  repeat  the  fil- 
tration, after  which  complete  the  washing  of  the  precipitate.  Determine  nitrogen 
in  the  washed  precipitate  and  filter  paper  as  directed  under  I,  18,  21  or  23,  mul- 
tiply by  6.3S  and  calculate  the  percentage  of  casein. 

In  samples  of  milk  which  have  been  preserved,  the  acetic  acid  should  be  added 
in  small  portions,  a  few  drops  at  a  time,  with  stirring,  and  the  addition  continued 
until  the  liquid  above  the  precipitate  becomes  clear,  or  very  nearly  so. 

5  Method  II.— Official. 

To  10  grams  of  the  milk  add  50  cc.  of  water  at  40°C.,  then  2  cc.  of  alum  solution 
saturated  at  40°C.,  or  higher.  Allow  the  precipitate  to  settle,  transfer  to  a  filter 
and  wash  with  cold  water.'  Determine  nitrogen  in  the  precipitate  and  filter  paper 
as  directed  under  I,  18,  21  or  23,  multiply  by  6. .38  and  calculate  the  percent- 
age of  casein. 

287 


288 


METHODS    OF   ANALYSIS 


[Chap. 


ALBUMIN. 

6  Method  I. — Tentative. 

Exactly  neutralize  the  filtrate,  obtained  in  4,  with  sodium  hydroxid  solution, 
add  0.3  cc.  of  10%  acetic  acid  and  heat  on  a  steam  bath  until  the  albumin  is  com- 
pletely precipitated.  Collect  the  precipitate  on  a  filter,  wash  with  cold  water  and 
determine  the  nitrogen  as  directed  under  I,  18,  21  or  23,  multiply  by  6.38  and  cal- 
culate the  percentage  of  albumin. 

7  Method  II. — Tentative. 

To  the  filtrate  obtained  from  the  casein  determination,  5,  add  0.3  cc.  of  10%  acetic 
acid,  boil  until  the  albumin  is  completely  precipitated  and  proceed  as  directed  in  6. 

LACTOSE. 
Optical  Method. — Tentative. 

8  REAGENTS. 

(a)  Acid  mercuric  nitrate  solution. — Dissolve  mercury  in  double  its  weight  of 
nitric  acid  (sp.  gr.  1.42)  and  dilute  with  an  equal  volmne  of  water. 

(b)  Mercuric  iodid  solution. — Dissolve  33.2  grams  of  potassium  iodid  and  13.5 
grams  of  mercuric  chlorid  in  20  cc.  of  glacial  acetic  acid  and  640  cc.  of  water. 

9  DETERMINATION. 

Determine  the  specific  gravity  of  the  milk  by  means  of  a  delicate  hydrometer 
or,  if  preferred,  a  pycnometer.  The  quantity  of  sample  to  be  taken  for  the  deter- 
mination varies  with  the  specific  gravity  and  is  to  be  measured  at  the  same  tempera- 
ture at  which  the  specific  gravity  is  taken.  The  volume  to  be  measured  will  be 
found  in  10  which  is  based  upon  twice  the  normal  weight  of  lactose  (32.9  grams  per 
100  metric  cc.)  for  the  Ventzke  sugar  scale. 

Place  the  quantity  of  milk  indicated  in  10  in  a  flask  graduated  at  102.6  cc.  Add 
1  cc.  of  the  acid  mercuric  nitrate  solution  or  30  cc.  of  the  mercuric  iodid  solution 
(an  excess  of  these  reagents  does  no  harm),  fill  to  the  mark,  shake,  filter  through  a 
dry  filter  and  polarize.  It  is  not  necessary  to  heat  before  polarizing.  If  a  200  mm. 
tube  is  used,  divide  the  polariscope  reading  by  2  (or,  if  a  400  mm.  tube  is  used,  by  4) 
to  obtain  the  per  cent  of  lactose  in  the  sample. 


10 


Table  19. 

Volumes  of  milk  corresponding  to  a  lactose  double  normal  weight^ 


VOLUME    OF    MILK   FOS    A. 

volume  of  milk  for  a 

SPECIFIC  GRAVITT  OP 

LACTOSE  DOUBLE  NOR- 

specific gravity  of 

lactose  double  nor- 

MILK 

MAL  WEIGHT 

MILK 

mal  weight 

(ventzke  scale) 

(ventzke  scale) 

1.024 

CC. 

64.25 

1.030 

cc. 

63.90 

1.025 

64.20 

1.031 

63.80 

1.026 

64.15 

1.032 

63.75 

1.027 

64.05 

1.033 

63.70 

1.028 

64.00 

1.034 

63.65 

1.029 

63.95 

1.035 

63.55 

1.036 

63.50 

XXII]  DAIRY    PRODUCTS  289 

1 1  Gravimetric  Method. — Official. 

Dilute  25  grams  of  the  milk  with  400  cc.  of  water  in  a  500  cc.  graduated  flask, 
add  10  cc.  of  copper  sulphate  solution  [VIII,  19  (a)]  and  about  7.5  cc.  of  a  potas- 
sium hydroxid  solution  of  such  strength  that  1  volume  is  just  sufficient  to  pre- 
cipitate completely  the  copper  as  hydroxid  from  1  volume  of  the  copper  sulphate 
solution.  Instead  of  potassium  hydroxid  solution  of  this  strength,  8.8  cc.  of  N/2 
sodium  hydroxid  solution  may  be  used.  After  the  addition  of  the  alkali  solution 
the  mixture  must  still  have  an  acid  reaction  and  contain  copper  in  solution.  Fill 
the  flask  to  the  500  cc.  mark,  mix,  filter  through  a  dry  filter  and  determine  lactose 
in  an  aliquot  of  the  filtrate  as  directed  under  VIII,  46  or  48. 

FAT. 

12  Roese-Gottlieb  Method'^. — Official. 

Weigh  10-11  grams  of  the  milk  into  a  Rohrig  tube  or  some  similar  apparatus, 
add  1.25  cc.  of  concentrated  ammonium  hydroxid  (2  cc.  if  the  sample  is  sour)  and 
mix  thoroughly.  Add  10  cc.  of  95%  alcohol  by  volume  and  mix  well.  Then  add 
25  cc.  of  washed  ether  and  shake  vigorously  for  30  seconds,  then  25  cc.  of  petro- 
leum ether  (redistilled  slowly  at  a  temperature  below  60°C.)  and  shake  again  for 
30  seconds.  Let  stand  20  minutes,  or  until  the  upper  liquid  is  practically  clear. 
Draw  off  as  much  as  possible  of  the  ether-fat  solution  (usually  0.5-0.8  cc.  will  be  left) 
into  a  weighed  flask  through  a  small,  quick-acting  filter.  The  flask  should  always 
be  weighed  with  a  similar  one  as  a  counterpoise.  Re-extract  the  liquid  remain- 
ing in  the  tube,  this  time  with  only  15  cc.  of  each  ether,  shake  vigorously  30  seconds 
with  each  and  allow  to  settle.  Draw  off  the  clear  solution  through  the  small  filter 
into  the  same  flask  as  before  and  wash  the  tip  of  spigot,  the  funnel  and  the  filter 
with  a  few  cc.  of  a  mixture  of  the  2  ethers  in  equal  parts.  For  absolutely  exact 
results  the  re-extraction  must  be  repeated.  This  third  extraction  yields  usually 
not  more  than  about  1  mg.  of  fat  (about  0.02%  on  a  4  gram  charge)  if  the  previous 
ether-fat  solutions  have  been  drawn  off  closely.  Evaporate  the  ethers  slowly  on  a 
•steam  bath,  then  dry  the  fat  in  a  boiling  water  oven  to  constant  weight. 

Confirm  the  purity  of  the  fat  by  dissolving  in  a  little  petroleum  ether.  Should 
a  residue  remain,  remove  the  fat  completely  with  petroleum  ether,  dry  the  residue, 
weigh  and  deduct  the  weight.  Finally  correct  this  weight  b)^  a  blank  determina- 
tion on  the  reagents  used. 

Babcock  Method. — Official. 

13  APPARATUS. 

(a)  Standard  Babcock  test  bottles. — The  standard  Babcock  test  bottles  for  milk 
and  cream  shall  be  as  follows: 

(1)  8%,  18  gram,  6  inch  milk  test  bottle.— The  total  per  cent  graduation  shall  be  8. 
The  total  height  of  the  bottle  shall  be  150-165  mm.  (5^-62  inches).  The  capac- 
ity of  the  bulb  up  to  the  junction  with  the  neck  shall  be  not  less  than  45  cc.  The 
graduated  portion  of  the  neck  shall  have  a  length  of  not  less  than  63.5  mm.  (2^ 
inches)  and  the  neck  shall  be  cylindrical  for  at  least  9  mm.  below  the  lowest  and 
aljove  the  highest  graduation  marks.  The  graduations  shall  represent  whole  per 
cents,  halves  and  tenths  of  a  per  cent. 

(2)  50%,  9  gram,  8  inch  cream  test  bottle.— The  total  per  cent  graduation  shall 
be  50.  The  total  height' of  the  bottle  shall  be  150-165  mm.  (5^61  inches).  The 
capacity  of  the  bulb  up  to  the  junction  with  the  neck  shall  be  not  less  than  45  cc.  The 
graduated  portion  of  the  neck  shall  have  a  length  of  not   less   than  63.5  mm.  (2^ 


290  METHODS    OF   ANALYSIS  [Chap. 

inches)  and  the  neck  shall  be  cylindrical  for  at  least  9  mm.  below  the  lowest  and 
above  the  highest  graduation  marks.  The  graduations  shall  represent  five  per  cents, 
whole  and  halves  of  a  per  cent. 

(3)  50%,  9  gram,  9  inch,  cream  test  bottle. — Same  as  (2)  except  that  the  total  height 
of  the  bottle  shall  be  210-225  mm.  (8l~Sl  inches). 

(b)  Centrifuge. 

(C)  Pipettes. — Graduated  to  deliver  17.6  cc.  of  water  at  20°C.  in  5-8  seconds. 

(d)  Graduates. — Capacity  17.5  cc.  or  a  Swedish  acid  bottle  delivering  that  amount. 


CALIBRATION   OF   APPARATUS. 


14 

(a)  Graduation. — The  unit  of  graduation  for  all  Babcock  glassware  shall  be  the 
true  cc.  (0.998877  gram  of  water  at  4°C.). 

With  bottles,  the  capacity  of  each  per  cent  on  the  scale  shall  be  0.20  cc. 

With  pipettes  and  graduates,  the  delivery  shall  be  the  intent  of  the  graduation; 
and  the  graduation  shall  be  read  with  the  bottom  of  the  meniscus  in  line  with  the 
mark. 

(b)  Testing. — The  method  for  testing  Babcock  bottles  shall  be  calibration  with 
mercury  (13.5471  grams  of  clean,  dry  mercury  at  20°C.,  to  be  equal  to  5%  on  the 
scale),  the  bottle  being  previously  filled  to  zero  with  mercury. 

The  mercury  and  cork,  alcohol  and  burette,  and  alcohol  and  brass  plunger 
methods  may  be  emploj'ed  for  the  rapid  testing  of  Babcock  bottles,  but  the  accuracy 
of  all  questionable  bottles  shall  be  determined  by  calibration  with  mercury. 

The  method  for  testing  pipettes  and  graduates  shall  be  calibration  by  measuring 
in  a  burette  the  quantity  of  water  (at  20°C.)  delivered. 

(C)  Limit  of  error. — For  standard  Babcock  milk  bottles  the  error  at  any  point 
of  the  scale  shall  not  exceed  0.1%. 

For  standard  Babcock  cream  bottles  the  error  at  any  point  of  the  scale  shall  not 
exceed  0.5  %. 

For  standard  milk  pipettes  the  error  shall  not  exceed  0.05  cc. 

For  acid  measures  the  error  shall  not  exceed  0.2  cc. 


15 


DETERMINATION. 


Pipette  17.6  cc.  of  the  carefully  mixed  sample  into  a  test  bottle  and  add  17.5 
cc.  of  commercial  sulphiu'ic  acid  (sp.  gr.  1.S2-1.83).  Mix  and,  when  the  curd  is 
dissolved,  centrifugalize  for  4  minutes  at  the  required  speed  for  the  machine  used. 
Add  boiling  water,  filling  to  the  neck  of  the  bottle,  and  whirl  for  1  minute;  again 
add  boiling  water  so  as  to  bring  the  fat  within  the  scale  on  the  neck  of  the  bottle, 
and,  after  whirling  for  1  minute  more,  read  the  length  of  the  fat  column,  making  the 
reading  at  57°-60°C.  at  which  temperature  the  fat  is  wholly  liquid.  The  reading 
gives  directly  the  per  cent  of  fat  in  the  milk. 

Details  of  the  manipulation  of  the  Babcock  test  and  its  application  in  the  analy- 
sis of  dairy  products  other  than  milk  arc  described  by  Farrington  and  WolP,  and 
Van  Slyke^ 

Added  Water. 

(In  conjunction  with  the  copper,  acetic  or  sour  serum  refraction  method, 

the  determination  of  the  ash  of  the  sour  serum  or  of  the  acetic  serum 

should  be  made  in  all  cases  where  the  indices  of  refraction 

fall  below  the  minimum  limit  so  as  to  eliminate 

all     possibility  of  abnormal  milk.) 


XXII]  DAIRY    PRODUCTS  291 

16  ACETIC  SERUM.-TENTATIVE. 

(a)  Zeiss  immersion  refractometer  reading. — To  100  cc.  of  milk  at  a  temperature 
of  about  20°C.  add  2  cc.  of  25%  acetic  acid  (sp.  gr.  1.035)  in  a  beaker  and  heat  the 
mixture,  covered  with  a  watch  glass,  in  a  water  bath  for  20  minutes  at  a  tempera- 
ture of  70°C.  Place  the  beaker  on  ice  water  for  10  minutes  and  separate  the  curd 
from  the  serum  by  filtering  through  a  12.5  cm.  folded  filter.  Transfer  about  35  cc. 
of  the  serum  to  1  of  the  beakers  that  accompanies  the  control-temperature  bath 
used  in  connection  with  the  Zeiss  immersion  refractometer,  and  take  the  refrac- 
tometer reading  at  exactly  20°C.,  using  a  thermometer  graduated  to  tenths  of  a 
degree.  A  reading  below  39  indicates  added  water;  between  39  and  40,  the  addition 
of  water  is  suspected. 

(b)  Ash. — Transfer  25  cc.  of  the  serum  to  a  flat-bottomed  platinum  dish  and 
evaporate  to  dryness  on  a  water  bath.  Then  heat  over  a  low  flame  (to  avoid  spat- 
tering) until  the  contents  are  thoroughly  charred,  place  the  dish  in  an  electric 
muffle,  preferably  with  pyrometer  attached,  and  ignite  to  a  white  ash  at  a  tem- 
perature not  greater  than  500°C.  (900°F.).  Cool  and  weigh.  Express  the  result 
as  grams  per  100  cc.  Results  below  0.715  gram  per  100  cc.  indicate  added  water. 
Multiply  by  the  factor  1.021  (dilution  of  the  acetic  serum  being  2%)  to  obtain  the 
result  on  the  sour  serum  ash. 

1 7  SOUR  SERUM.— TENTATIVE. 

(a)  Zeiss  immersion  refractometer  reading. — Allow  the  milk  to  sour  spontane- 
ously, filter  and  determine  the  immersion  refractometer  reading  of  the  clear  serum 
at  20°C.     A  reading  below  38.3  indicates  added  water. 

(b)  ^s/i^— Determine  the  ash  in  25  cc.  of  the  serum,  obtained  in  (a),  as  directed 
in  16  (b).     Results  below  0.730  gram  per  100  cc.  indicate  added  water. 

18  ZEISS  REFRACTOMETER  READING  OF  COPPER  SERUM.— TENTATIVE. 

To  1  volume  of  copper  sulphate  solution  (72.5  grams  of  copper  sulphate  per 
liter,  adjusted  if  necessary  to  read  36  at  20°C.  on  the  scale  of  the  Zeiss  immersion 
refractometer,  or,  to  a  specific  gravity  of  1.0443  at  ^^)  add  4  volumes  of  milk.  • 
Shake  well  and  filter.  Determine  the  Zeiss  refractometer  reading  of  the  clear 
serum  at  20°C.    A  reading  below  36  indicates  added  water. 

GELATIN, 

19  Qualitative  Test. — Tentative. 

To  10  cc.  of  the  milk  add  an  equal  volume  of  acid  mercuric  nitrate  solution  (mer- 
cury dissolved  in  twice  its  weight  of  nitric  acid  (sp.  gr.  1.42)  and  this  solution 
diluted  to  25  times  its  volume  with  water),  shake  the  mixture,  add  20  cc.  of  water, 
shake  again,  allow  to  stand  5  minutes  and  filter.  If  much  gelatin  is  present,  the 
filtrate  will  be  opalescent  and  cannot  be  obtained  quite  clear.  To  a  portion  of  the 
filtrate  contained  in  a  test  tube,  add  an  equal  volume  of  saturated  aqueous  picric 
acid  solution.  A  yellow  precipitate  will  be  produced  in  the  presence  of  any  con- 
siderable amount  of  gelatin,  while  smaller  amounts  will  be  indicated  by  a  cloudi- 
ness.    In  the  absence  of  gelatin  the  filtrate  will  remain  perfectly  clear. 

20  PRESERVATIVES.— TENTATIVE. 

Proceed  as  directed  under  X.  To  test  for  salicylic  or  benzoic  acid  acidify  100 
cc.  of  the  milk  with  5  cc.  of  hydrochloric  acid  (1  to  3),  shake  until  curdled,  filter 
and  treat  the  clear  filtrate  as  directed  under  X,  2,  3  or  8. 


292  METHODS    OF   ANALYSIS  [Chap. 

To  test  for  formaldehyde  proceed  as  directed  under  X,  17,  18,  19,  20,  21,  22, 


or 


23,  applying  the  test  directly  to  the  milk. 


COLORING  MATTERS. 

21  Leach  Method. — Tentative. 

Warm  about  150  cc.  of  milk  in  a  casserole  over  a  flame  and  add  about  5  cc.  of 
acetic  acid,  then  slowly  continue  the  heating  nearly  to  the  boiling  point  while  stir- 
ring. Gather  the  curd,  when  possible,  into  one  mass  with  a  stirring  rod  and  pour 
off  the  whey.  If  the  curd  breaks  up  into  small  flecks,  separate  from  the  whey  by 
straining  through  a  sieve  or  colander.  Press  the  curd  free  from  adhering  liquid, 
transfer  to  a  small  flask  and  macerate  for  several  hours,  preferably  overnight,  in 
about  50  cc.  of  ether,  the  flask  being  tightly  corked  and  shaken  at  intervals.  De- 
cant the  ether  extract  into  an  evaporating  dish,  remove  the  ether  by  evaporation 
and  test  the  fatty  residue  for  annatto  as  directed  in  XI,  24. 

The  curd  of  an  uncoloredmilk  is  perfectly  white  after  complete  extraction  with 
ether,  as  is  also  that  of  a  milk  colored  with  annatto.  If  the  extracted  fat-free  curd 
is  distinctly  colored  an  orange  or  yellowish  color,  a  coal  tar  dye  is  indicated.  In 
many  cases  upon  treating  a  lump  of  a  fat-free  curd  in  a  test  tube  with  a  little  strong 
hydrochloric  acid  the  color  changes  to  pink,  indicating  the  presence  of  a  dye  simi- 
lar to  aniline  yellow  or  butter  yellow  or  perhaps  one  of  the  acid  azo  yellows  or 
oranges.  In  such  cases,  separate  and  identify  the  coloring  matter  present  in  the 
curd  as  directed  under  XI.  If  aniline  yellow,  butter  yellow,  or  other  oil-soluble 
•dye  is  present,  the  greater  part  will  be  found  in  the  ether  extract  containing  the 
fat.     In  such  cases  proceed  as  directed  under  XI,  3. 

In  some  cases  the  presence  of  coal  tar  dyes  can  be  detected  by  treating  about 
10  cc.  of  the  milk  directly  with  an  equal  volume  of  hydrochloric  acid  (sp.  gr.  1.20) 
in  a  porcelain  casserole,  giving  the  dish  a  slight  rotary  motion.  In  the  presence  of 
some  dyes  the  separated  curd  acquires  a  pink  coloration. 

CREAM. 

22  SOLIDS.-OFFICIAL. 

Proceed  as  directed  in  1 ,  employing  2-3  grams  of  the  sample. 

23  ASH.— OFFICIAL. 
Proceed  as  directed  under  2. 

24  TOTAL  NITROGEN.-OFFICIAL. 
Proceed  as  directed  under  3. 

LACTOSE. 

25  Gravimetric  Method. — Official. 

Proceed  as  directed  under  1 1 . 

FAT. 

26  Extraction  Method. — Official. 

Weigh  4-5  grams  of  the  homogeneous  sample  into  a  Rohrig  tube  or  similar  appa- 
ratus, dilute  with  water  to  about  10.5  cc.  and  proceed  as  directed  under  12. 

27  Babcock  Method. — Official. 

Weigh  9  or  18  grams,  depending  upon  the  fat  content  of  the  sample,  into  a  stand- 
ard Babcock  cream  bottle  and  proceed  as  directed  under  15. 


XXII]  DAIRY    PRODUCTS  293 

28  GELATIN.-TENTATIVE. 
Proceed  as  directed  under  19. 

29  COLORING  MATTERS.— TENTATIVE. 

Proceed  as  directed  under  XI,  particularly  3  and  24  for  the  detection  of  oil- 
soluble  coal  tar  dyes  and  annatto. 

30  PRESERVATIVES.-TENTATIVE. 
Proceed  as  directed  under  X. 

31  CONDENSED  MILK  (UNSWEETENED). 

Dilute  40  grams  of  the  homogeneous  sample  with  60  grams  of  water  and  pro- 
ceed as  directed  under  1  to  15,  inclusive,  19,  20  and  21,  correcting  the  results  for 
the  dilution. 

CONDENSED  MILK  (SWEETENED). 

32  PREPARATION  OF  SAMPLE.-OFFICIAL. 

If  cold,  place  the  can  in  water  at  30°-35°C.  until  warm.  Open,  scrape  out  all 
milk  adhering  to  the  interior  of  the  can  and  mix  by  transferring  the  contents  to  a 
dish  sufficiently  large  to  stir  thoroughly  and  make  the  whole  mass  homogeneous. 
Weigh  100  grams  into  a  500  cc.  flask  and  make  up  to  the  mark  with  water.  If  the 
milk  will  not  dissolve  completelj',  weigh  out  each  portion  for  analysis  separately. 

33  TOTAL  SOLIDS.-OFFICIAL. 

Use  10  cc.  of  the  solution,  prepared  as  directed  in  32,  and  proceed  as  directed  in 
1 ,  drying  either  on  sand  or  asbestos  fiber. 

34  ASH.— OFFICIAL. 

Evaporate  10  cc.  of  the  solution,  prepared  as  directed  in  32,  to  dryness  on  a 
water  bath  and  ignite  the  residue  as  directed  under  VIII,  4. 

35  PROTEIN.— OFFICIAL. 

Determine  nitrogen  as  directed  under  I,  18,  21  or  23,  using  10  cc.  of  the  solu- 
tion, prepared  as  directed  in  32,  without  evaporation  and  multiply  by  6.38. 

38  LACTOSE.-OFFICIAL. 

Dilute  100  cc.  of  the  solution,  prepared  as  directed  in  32,  in  a  250  cc.  flask  to 
about  200  cc,  add  6  cc.  of  Fehling's  copper  sulphate  solution  [VIII,  19  (a)]  and  make 
up  to  the  mark.     Filter  through  a  dry  filter  and  determine  lactose  as  directed  in 

VIII,  46  or  48. 

37  FAT  OR  ETHER  EXTRACT. 

Roese-Gottlieb  Method.— Official. 

Weigh  4-5  grams  of  the  homogeneous  sample  into  a  Rohrig  tube  or  some  similar 
apparatus,  dilute  with  water  to  about  10.5  cc.  and  proceed  as  directed  under  12. 

38  SUCROSE.-TENTATIVE. 

Determine  sucrose  by  difference,  deducting  the  milk  solids  (lactose,  protein,  fat 
and  ash)  from  the  total  solids. 


294  METHODS    OF   ANALYSIS  [Chap. 

BUTTER  AND  ITS  SUBSTITUTES. 

39  PREPARATION  OF  SAMPLE.-OFFICIAL. 

If  large  quantities  of  butter  are  to  be  sampled,  use  a  butter  trier  or  sampler. 
Melt  completely  the  portions  thus  drawn,  100-500  grams,  in  a  closed  vessel  at  as 
low  a  temperature  as  possible.  When  softened,  cool  and,  at  the  same  time,  shake 
the  mass  violently  until  it  is  homogeneous  and  solidified  sufficiently  to  prevent  the 
separation  of  the  water  and  fat.  Then  pour  a  portion  into  the  vessel  from  which 
it  is  to  be  weighed.  The  sample  should  completely  or  nearly  fill  the  vessel  and 
should  be  kept  in  a  cool  place  until  analyzed. 

40  MOISTURE.— OFFICIAL. 

Weigh  1.5-2.5  grams  of  the  sample  into  a  flat-bottomed  dish,  having  a  surface 
of  at  least  20  sq.  cm.,  dry  at  the  temperature  of  boiling  water  and  weigh  at  hourly 
intervals  until  the  weight  becomes  constant.  The  use  of  clean,  dry  sand  or  asbestos 
is  admissible. 

ETHER  EXTRACT. 

41  Indirect  Method. — Official. 

Dissolve  the  dry  butter,  obtained  in  the  moisture  determination  in  which  no 
absorbent  was  used,  in  absolute  ether  or  petroleum  ether,  transfer  to  a  weighed 
Gooch,  with  the  aid  of  a  wash  bottle  filled  with  the  solvent  and  wash  until  free 
from  fat.  Dry  the  Gooch  and  contents  at  the  temperature  of  boiling  water  until 
the  weight  is  constant  and  determine  the  fat. 

42  Direct  Method.— Official. 

From  the  dry  butter,  obtained  in  the  determination  of  moisture,  either  with  or 
without  the  use  of  an  absorbent,  extract  the  fat  with  anhydrous,  alcohol-free  ether, 
receiving  the  solution  in  a  weighed  flask.  Evaporate  the  ether,  dry  the  extract  at 
the  temperature  of  boiling  water  and  weigh  at  hourly  intervals  until  the  weight 
is  constant. 

43  CASEIN,  ASH  AND  CHLORIN.— OFFICIAL. 

Cover  the  crucible,  containing  the  residue  from  the  fat  determination  by  the 
indirect  method,  41,  and  heat  gently  at  first,  then  raise  the  temperature  gradually 
to  just  below  redness.  The  cover  may  then  be  removed  and  heating  continued 
until  the  contents  of  the  crucible  are  white.  The  loss  in  weight  represents  casein, 
and  the  residue  in  the  crucible,  mineral  matter.  Dissolve  this  mineral  matter  in 
water  slightly  acidified  with  nitric  acid  and  determine  chlorin,  either  gravimetri- 
cally  as  directed  under  I,  16  (a),  or  volumetrically  as  directed  under  III,  15. 

44  SALT.-OFFICIAL. 

Weigh  in  a  counterpoised  beaker  5-10  grams  of  butter,  using  portions  of  about 
1  gram  from  different  parts  of  the  sample.  Add  about  20  cc.  of  hot  water  and,  after 
the  butter  is  melted,  transfer  the  whole  to  a  separatory  funnel.  Insert  the  stopper 
and  shake  for  a  few  moments.  Let  stand  until  all  the  fat  has  collected  on  the  top 
of  the  water,  then  draw  off  the  latter  into  a  flask,  being  careful  to  let  none  of  the 
fat  globules  pass.  Again  add  hot  water,  rinsing  the  beaker,  and  repeat  the  extrac- 
tion 10-15  times,  using  10-20  cc.  of  water  each  time.  The  washings  will  contain  all 
but  a  mere  trace  of  the  sodium  chlorid  originally  present  in  the  butter.  Determine 
the  amount  in  the  whole  or  an  aliquot  of  the  liquid  by  titration  with  standard  silver 
nitrate,  using  potassium  chromate  as  an  indicator. 


xxii]  dairy  products  295 

Fat. 

45  preparation  of  sample.— official. 

Melt  the  butter  and  keep  in  a  dry  place  at  about  60°C.  for  2-3  hours  or  until  the 
water  and  curd  have  entirely  separated.  Filter  the  clear,  supernatant  fat  through 
a  dry  filter  paper  in  a  hot  water  funnel  or  in  an  oven  at  about  60°C.  If  the  filtered 
liquid  fat  is  not  perfectly  clear,  refilter. 

46  EXAMINATION. 
Proceed  as  directed  under  XXIII. 

47  Microscopic  Method. — Official. 

Place  on  a  slide  a  small  portion  of  the  fresh,  unmelted  sample  taken  from  the 
inside  of  the  mass,  add  a  drop  of  pure  olive  oil,  apply  a  cover-glass  with  gentle 
pressure,  and  examine  with  a  magnification  of  120-150  diameters  for  crystals  of 
lard,  etc.  Examine  the  same  specimen  with  polarized  light  and  a  selenite  plate 
without  the  use  of  oil.  Pure  fresh  butter  will  show  neither  crystals  nor  a  parti- 
colored field  with  selenite.  Renovated  butter  or  other  fats  melted  and  cooled  and 
mixed  with  butter  will  usually  present  crystals  and  variegated  colors  with  the 
selenite  plate. 

For  further  microscopic  study  dissolve  in  a  test  tube  3-^  cc.  of  the  fat  in  15  cc. 
of  ether.  Close  the  tube  with  a  loose  plug  of  cotton  wool  and  allow  to  stand  12-24 
hours  at  20°-25°C.  When  crystals  form  at  the  bottom  of  the  tube,  remove  with  a 
pipette,  glass  rod  or  tube,  place  on  a  slide,  cover  and  examine  under  a  microscope. 
The  crystals  formed  by  later  deposits  may  be  examined  in  a  similar  way.  Com- 
pare with  crystals  obtained  in  the  same  way  from  samples  of  known  purity. 

48  PRESERVATIVES.— TENTATIVE. 
Proceed  as  directed  under  X. 

49  COLORING  MATTERS.— TENTATIATE. 

Pour  about  2  grams  of  the  filtered  fat,  dissolved  in  ether,  into  each  of  2  test  tubes. 
Into  one  of  the  tubes  pour  1-2  cc.  of  hydrochloric  acid  and  into  the  other  about  the 
same  volume  of  dilute  potassium  hydroxid  solution.  Shake  the  tubes  well  and 
allow  to  stand.  In  the  presence  of  azo  dyes  the  test  tube  to  which  the  acid  has  been 
added  will  show  a  pink  to  wine-red  coloration,  while  the  potash  solution  in  the 
other  tube  will  show  no  color.  If,  on  the  other  hand,  annatto  or  other  vegetable 
color  has  been  used,  the  potash  solution  will  be  colored  yellow,  while  no  color  will 
be  apparent  in  the  acid  solution. 

General  test. — Proceed  as  directed  under  XI,  particularly  3  and  24,  for  the  detec- 
tion of  oil-soluble  coloring  matters  and  annatto. 

RENOVATED  BUTTER  AND  OLEOMARGARINE. 

50  Foam  Test.— Tentative. 

Heat  2-3  grams  of  the  sample,  either  in  a  spoon  or  dish,  over  a  free  flame.  True 
butter  will  foam  abundalitly,  whereas  process  butter  will  bump  and  sputter,  like 
hot  grease,  without  foaming.  Oleomargarine  behaves  like  process  butter,  but 
chemical  tests  will  determine  whether  the  sample  is  oleomargarine  or  butter. 


296  METHODS    OF   ANALYSIS  [Chap. 

51  Melted  Fat  Test.— Tentative. 

Melt  50-100  grams  of  butter  or  renovated  butter  at  50°C.  The  curd  from  butter 
will  settle,  leaving  a  clear  supernatant  fat;  in  the  case  of  renovated  butter,  the 
supernatant  fat  remains  more  or  less  turbid. 

CHEESE. 

52  SELECTION  AND  PREPARATION  OF  THE  SAMPLE.— OFFICIAL. 

When  the  cheese  can  be  cut,  take  a  narrow,  wedge-shaped  segment  reaching 
from  the  outer  edge  to  the  center  of  the  cheese.  Cut  this  into  strips  and  pass  3 
times  through  a  sausage  machine.  When  the  cheese  cannot  be  cut,  take  the  sample 
with  a  cheese  trier.  If  only  1  plug  can  be  obtained,  take  it  perpendicular  to  the 
surface  of  the  cheese  at  a  point  one  third  the  distance  from  the  edge  to  the  center 
and  extending  either  entirely  or  half  way  through  it.  When  possible,  draw  3  plugs, 
1  from  the  center,  1  from  a  point  near  the  outer  edge,  and  1  from  a  point  half  way 
between  the  other  2.  For  inspection  purposes  reject  the  rind  but  for  investigations 
requiring  the  absolute  amount  of  fat  in  the  cheese  include  the  rind  in  the  sample. 
Either  grind  the  plugs  in  a  sausage  machine  or  cut  them  very  finely  and  mix  carefully, 
preferably  the  former. 

53  MOISTURE.— TENTATIVE. 

Place  2-3  grams  of  very  short  fiber  asbestos  (the  long  fiber  may  be  made  suit- 
able by  rubbing  it  through  a  fine  sieve)  in  a  flat-bottomed  platinum  dish,  6-7  cm. 
in  diameter,  and  press  the  asbestos  down  firmly.  Place  in  the  dish  a  glass  rod, 
about  5  mm.  in  diameter  and  slightly  longer  than  the  diameter  of  the  dish.  Ignite, 
cool  and  weigh  the  dish  and  contents.  Then  weigh  into  the  dish  4-5  grams  of  the 
sample,  prepared  as  directed  under  52,  and  mix  the  cheese  and  asbestos  intimately 
with  the  glass  rod  until  the  mass  is  homogeneous.  Leave  the  mass  in  as  loose  a  con- 
dition as  possible  to  facilitate  the  drying.  Dry  the  mixture  in  an  oven  at  100°C. 
and  weigh  at  1-1|  hour  intervals  until  the  weight  becomes  constant  (3  weighings  are 
usually  sufficient). 

54  ASH  AND  SALT.-OFFICLAX. 

The  dry  residue  from  the  moisture  determination  may  be  used  for  the  determi- 
nation of  ash.  If  the  cheese  be  rich  in  fat,  the  asbestos  will  be  saturated  with  it. 
Ignite  cautiously  to  avoid  spattering  and  remove  the  lamp  while  the  fat  is  burn- 
ing off.  When  the  flame  has  died  out,  complete  the  burning  in  a  muffle  at  low  red- 
ness.    When  desired,  the  salt  may  be  determined  in  the  ash,  as  directed  in  43. 

55  NITROGEN.— OFFICIAL. 

Determine  nitrogen  as  directed  under  I,  18,  21  or  23,  using  about  2  grams  of 
cheese,  and  multiply  the  percentage  of  nitrogen  by  6.38  to  obtain  the  per  cent 
of  nitrogen  compounds. 

55  ACIDITY.— TENTATIVE. 

To  10  grams  of  finely  divided  cheese  add  water  at  a  temperature  of  40°C.  until 
the  volume  equals  105  cc,  shake  vigorously  and  filter.  Titrate  25  cc.  portions  of 
the  filtrate,  representing  2.5  grams  of  the  sample,  with  standard  sodium  hydroxid, 
preferably  N/10,  using  phenolphthalein  as  an  indicator.  Express  the  result  in 
terms  of  lactic  acid. 


XXII]  DAIRY    PRODUCTS  297 

57  COLORING  MATTERS.-TENTATIVE. 
Proceed  as  directed  under  XI. 

FAT. 

58  PREPARATION  OF  SAMPLE.— TENTATIVE. 

(a)  Alkaline  extraction. — Treat  about  300  grams  of  the  cheese,  cut  into  frag- 
ments the  size  of  a  pea,  with  700  cc.  of  5%  potassium  hydroxid  solution  at  20°C.  in 
a  large,  wide-necked  flask,  shaking  vigorously  to  dissolve  the  casein.  In  5-10 
minutes  the  casein  will  be  dissolved  and  the  fat  will  rise  to  the  surface  in  lumps. 
Collect  the  lumps  of  fat  into  as  large  a  mass  as  possible  by  shaking  gently.  Pour 
cold  water  into  the  flask  until  the  fat  is  driven  up  into  the  neck  and  remove  it  by 
suitable  means.  Wash  the  fat  thus  obtained  with  just  sufficient  water  to  remove 
the  residue  of  the  alkali  which  it  may  contain.  The  fat  is  not  perceptibly  attacked 
by  the  alkali  in  this  treatment,  is  practically  all  separated  in  a  short  time  and  is  then 
easily  prepared  for  chemical  analysis  by  filtering  and  drying  as  directed  in  45. 

(b)  Acid  extraction. — Pass  the  cheese  through  a  grinding  machine,  transfer  to  a 
large  flask  and  cover  with  warm  water,  using  1  cc.  for  every  gram  of  cheese.  Shake 
thoroughly  and  add  sulphuric  acid  (sp.  gr.  1.82-1.825)  slowly  and  in  small  quanti- 
ties, shaking  after  each  addition  of  acid.  The  total  amount  of  acid  used  should 
be  the  same  as  the  amount  of  water  employed.  Remove  the  fat,  which  separates 
after  standing  a  few  minutes,  by  means  of  a  separatory  funnel,  wash  free  from  acid, 
filter  and  dry  as  directed  in  45. 

59  EXAMINATION.— TENTATIVE, 
Proceed  as  directed  under  XXIII. 

Estimation. 

60  Gravimetric  Method. — Official. 

Cover  the  perforations  in  the  bottom  of  an  extraction  tube  with  dry  asbestos 
felt,  and  place  on  this  a  mixture  containing  equal  parts  of  anhydrous  copper  sul- 
phate and  pure,  dry  sand  to  a  depth  of  about  5  cm.,  packing  loosely.  Cover  the 
upper  surface  of  this  material  with  a  layer  of  asbestos.  Place  on  this  2-n5  grams  of 
the  sample  and  extract  with  anhydrous  ether  for  5  hours  in  a  continuous  extrac- 
tion apparatus.  Remove  the  cheese  and  grind  it  with  pure  sand  in  a  mortar  to  a 
fine  powder,  return  the  mixed  cheese  and  sand  to  the  extraction  tube,  wash  the  mor- 
tar with  ether,  add  the  washings  to  the  tube  and  continue  the  extraction  for  at  least 
10  hours. 

61  Schmidt-Bondzynski  Method,  Modified. — Tentative. 

Rub  up,  by  means  of  a  glass  rod,  1  gram  of  the  homogeneous  sample  with  9  cc.  of 
water  and  1  cc.  of  concentrated  ammonium  hydroxid  in  a  narrow  100-125  cc.  beaker. 
Digest  the  mixture  at  a  low  heat  until  the  casein  is  well  softened;  neutralize  with 
concentrated  hydrochloric  acid,  using  litmus  as  an  indicator  and  add  10  cc.  more 
of  concentrated  hydrochloric  acid.  Add  a  pinch  of  sand  to  prevent  bmnping  and 
boil  gently  for  5  minutes,  keeping  the  beaker  covered  with  a  watch  glass.  Cool 
the  solution,  transfer  to  .a  Rohrig  tube  or  some  similar  apparatus,  rinse  the  beaker 
with  25  cc.  of  washed  ethyl  ether  and  shake  well.  Add  25  cc.  of  redistilled  petro- 
leum ether  (b.  p.  below  65°C.),  let  the  solutions  separate  and  proceed  from  this 
point  as  directed  in  12. 


298  METHODS    OF   ANALYSIS 

62  Babcock  Method. — Tentative. 

Weigh  about  6  grams  of  the  cheese  in  a  tared  dish.  Add  10  cc.  of  boiling  water  and 
stir  with  a  rod  until  the  cheese  softens  and  an  even  emulsion  is  formed,  preferably 
adding  a  few  drops  of  strong  ammonium  hydroxid,  and  keep  the  beaker  in  hot  water 
until  the  emulsion  is  nearly  completed  and  the  mass  free  from  lumps.  If  the  sample 
is  a  whole  milk  cheese,  employ  a  Babcock  cream  bottle.  After  cooling,  transfer  the 
contents  of  the  beaker  to  the  test  bottle  by  adding  to  the  beaker  about  half  of  the 
17.6  cc.  of  sulphuric  acid  usually  employed  in  this  test,  stirring  with  a  rod,  and 
pouring  carefully  into  the  bottle,  using  the  remainder  of  the  acid  in  2  portions  for 
washing  out  the  beaker.  Then  proceed  as  directed  in  15.  Multiply  the  fat  reading 
by  18  and  divide  by  the  weight  of  the  sample  taken  to  obtain  the  per  cent  of  fat. 

BIBLIOGRAPHY. 

1  Browne.     Handbook  of  Sugar  Analysis.     1912,  p.  252. 

2  Z.  Nahr.  Genussm.,  1905,  9:  531. 

3  Farrington  and  WoU.     Testing  Milk  and  Its  Products.  23rd  ed.,  1916. 

*Van  Slyke.  Modern  Methods  of  Testing  Milk  and  Milk  Products.  Rev.  ed.. 
1907. 

sChem..  Ztg.,  1908,  32:617. 


XXIII.    FATS  AND  OILS. 

1  PREPARATION  OF  SAMPLE.— OFFICIAL. 

Melt  solid  fats  and  filter  by  means  of  a  hot  water  funnel  or  similar  apparatus. 
Make  the  different  determinations  on  samples  of  this  melted,  homogeneous  mass. 
Filter  oils  that  are  not  clear.  Keep  oils  and  fats  in  a  cool  place  and  protected  from 
light  and  air,  otherwise  they  will  soon  become  rancid.  Weigh  out  at  one  time  as 
many  portions  as  are  needed  for  the  various  determinations,  using  a  small  beaker 
or  weighing  burette. 

SPECIFIC  GRAVITY. 
.     20°C.       ^     .  .. 


20  °C 
Determine  the  specific  gravity  of  the  oil  at  -^  by  means  of  a  pycnometer. 


If  the  specific  gravity  of  the  oil  is  determined  at  other  than  standard  tempera- 
ture, the  approximate  specific  gravity  at  20°C.  may  be  calculated  by  means  of  the 
following  formula: 

G    =  G'  +  0.0007  (T-20°C.)  in  which 
G    =  specific  gravity  at  20°C.; 

T°C 
G'  =  specific  gravity  at  -^  ; 

T   =  temperature  at  which  the  specific  gravity  was  determined; 
0.0007   =  mean  correction'  for  1°C. 

At  the  Temperature  of  Boiling  Water.— OflBciaL 

3  STANDARDIZATION   OF   FLASKS. 

(a)  Fill  a  tared,  25-30  cc.  specific  gravity  flask  with  freshly  boiled,  hot  water. 
Place  in  a  briskly  boiling  water  bath  for  30  minutes,  replacing  any  evaporation 
from  the  flask  by  the  addition  of  boiling  water.  Then  insert  the  stopper,  previous- 
ly heated  to  100°C.,  remove  the  flask,  cool  and  weigh. 

(b)  The  following  formula  may  be  used  for  calculating  the  weight  of  water  (W^) 
which  a  given  flask  will  hold  at  T°  (weighed  in  air  with  brass  weights  at  the  tempera- 
ture of  the  room)  from  the  weight  of  water  (W*^)  (weighed  in  air  with  brass  weights 
at  the  temperature  of  the  room)  contained  therein  at  t°: 

W^  =  W*  ^  [1  +  0.000026  (T  -  t)]  in  which 

d' 
d'^  =  the  density  of  water  at  T°; 
d*  =  the  density  of  water  at  t°. 

4  DETER.MINATION. 

Fill  the  flask,  dried  at  the  temperature  of  boiling  water,  with  the  dry,  hot,  freshly 
filtered  fat,  which  should  be  entirely  free  from  air  bubbles;  keep  in  the  water  bath 
30  minutes  at  the  temperature  of  boiling  water.  Insert  the  stopper,  previously 
heated  to  100°C.,  cool  and  weigh.  Divide  the  weight  of  contained  fat  by  the  weight 
of  contained  water  previously  found  to  obtain  the  specific  gravity. 

The  weight  of  water  at  boiling  temperature  must  be  determined  under  the  baro- 
metric conditions  prevailing  at  the  time  the  determination  is  made. 

299 


300  METHODS   OF   ANALYSIS  [Chap. 

INDEX  OF  REFRACTION. 
5  General  Directions.— Tentative. 

Place  the  instrument  in  such  a  position  that  diffuse  daylight  or  any  form  of  arti- 
ficial light  can  readily  be  obtained  for  illumination.  Circulate  through  the  prisms 
a  stream  of  water  of  constant  temperature. 

Determine  the  index  of  refraction  with  any  standard  instrument,  reading  oils  at 
20°C.  and  fats  at  40°C. 

The  readings  of  the  Zeiss  butyro-refractometer  can  be  reduced  to  standard  tem- 
perature by  the  following  formula^: 

R  =  R'  4-  0.55  (T'  -  T)  in  which 
R    =  the  reading  reduced  to  temperature  T; 
R'  =  the  reading  at  T'C. 

T'  =  the  temperature  at  which  reading  R'  is  made; 
T    =  the  standard  temperature; 
0.55  =  correction  in  scale  divisions  for  1°C. 
With  oils  the  factor  0.58  is  substituted  in  the  formula  for  0.55,  since  they  have  a 
higher  index  of  refraction. 

The  readings  of  instruments,  which  give  the  index  of  refraction  directly,  can  be 
reduced  to  standard  temperature  by  substituting  the  factor  0.000365  for  0.55  in  the 
formula.     As  the  temperature  rises  the  refractive  index  falls. 

The  instrument  used  may  be  standardized  with  water  at  20°C.,  the  theoretical 
refractive  index  of  water  at  that  temperature  being  1.3330.  Any  correction  found 
should  be  made  on  all  readings. 

The  index  of  refraction  varies  directly  with  the  specific  gravity.  If  the  results 
appear  abnormal,  compare  the  specific  refractive  power^  with  the  normal.     Calcu- 

N  -  1 
late  the  specific   refractive   power  from   the   formula  — — ,  in  which  N  equals 

the  refractive  index  and  D  the  specific  gravity.     According  to  Procter*  the  Lorenz 

N2-1  N-1 

formula  gives  much  more  satisfactory  results  than — — — . 

g  By  Means  of  the  Abbe  Refractometer.— Official. 

To  charge  the  instrument,  open  the  double  prism  by  means  of  the  screw  head 
and  place  a  few  drops  of  the  sample  on  the  prism  or,  if  preferred,  open  the  prisms 
slightly  by  turning  the  screw  head  and  pour  a  few  drops  of  the  sample  into  the 
funnel-shaped  aperture  between  the  prisms.  Then  close  the  prisms  firmly  by 
tightening  the  screw  head.  Allow  the  instrument  to  stand  for  a  few  minutes 
before  the  reading  is  made,  so  that  the  temperature  of  the  sample  and  the  instru- 
ment will  be  the  same. 

The  method  of  measurement  is  based  upon  the  observation  of  the  position  of  the 
border  line  of  total  reflection  in  relation  to  the  faces  of  a  prism  of  flint  glass.  Bring 
this  border  line  into  the  field  of  vision  of.  the  telescope  by  rotating  the  double  prism 
by  means  of  the  alidade  in  the  following  manner:  Hold  the  sector  firmly,  move  the 
alidade  backward  or  forward  until  the  field  of  vision  is  divided  into  a  light  and  a 
dark  portion.  The  line  dividing  these  portions  is  the  "border  line".  This,  as  a 
rule,  will  not  be  a  sharp  line  but  a  band  of  color  which  is  eliminated  by 
rotating  the  screw  head  of  the  compensator  until  a  sharp,  colorless  line  is  obtained. 
The  border  line  should  now  be  adjusted  so  that  it  falls  on  the  point  of  intersection 
of  the  2  cross  hairs.  Read  the  refractive  index  of  the  substance  directly  on  the 
scale  of  the  sector.  Check  the  correctness  of  the  instrument,  as  directed  under  5, 
or  by  means  of  the  quartz  plate  which  accompanies  it,  using  monobromnaphtha- 
lene,  and  make  the  necessary  correction  in  the  reading. 


xxmi 


FATS   AND    OILS 


301 


7  By  Means  of  the  Zeiss  Butyro-Refractometer.— Official. 

Place  2  or  3  drops  of  the  filtered  fat  on  the  surface  of  the  lower  prism.  Close  the 
prisms  and  adjust  the  mirror  until  it  gives  the  sharpest  reading.  If  the  reading 
be  indistinct  after  running  water  of  a  constant  temperature  through  the  instru- 
ment for  some  time,  the  fat  is  unevenly  distributed  on  the  surfaces  of  the  prism. 
As  the  index  of  refraction  is  greatly  affected  by  temperature,  care  must  be  used  to 
keep  the  latter  constant.  The  instrument  should  be  carefully  adjusted  by  means  of 
the  standard  fluid  which  is  supplied  with  it.  Convert  the  degrees  of  the  instru- 
ment into  refractive  indices  from  8. 


8 


Table  20. 
BtUyro-refractometer  readings  and  indices  of  refraction. 


REjVDINO 

INDEX  OF 

READING 

INDEX  OF 

READING 

INDEX  OF 

READING 

INDEX  OF 

REFRACTION 

REFRACTION 

REFRACTION 

REFRACTION 

40.0 

1.4524 

50.0 

1.4593 

60,0 

1.4659 

70.0 

1.4723 

40.5 

1.4527 

50.5 

1.4596 

60,5 

1.4662 

70.5 

1.4726 

41.0 

1.4531 

51.0 

1.4600 

61.0 

1.4665 

71.0 

1.4729 

41.5 

1.4534 

51.5 

1.4603 

61.5 

1.4668 

71.5 

1.4732 

42.0 

1,4538 

52.0 

1.4607 

62.0 

1.4672 

72.0 

1.4735 

42.5 

1.4541 

52.5 

1.4610 

62.5 

1.4675 

72.5 

1.4738 

43.0 

1.4545 

53.0 

1.4613 

63.0 

1.4678 

73.0 

1.4741 

43.5 

1.4.548 

53.5 

1.4616 

63.5 

1.4681 

73.5 

1.4744 

44.0 

1.4552 

54.0 

1.4619 

64.0 

1.4685 

74.0 

1.4747 

44.5 

1.4555 

54.5 

1.4623 

64.5 

1.4688 

74.5 

1.4750 

45.0 

1.4558 

55.0 

1.4626 

65.0 

1.4691 

75.0 

1.4753 

45.5 

1.4562 

55.5 

1.4629 

65.5 

1.4694 

75.5 

1.4756 

46.0 

1.4565 

56.0 

1.4633 

66.0 

1.4697 

76.0 

1.4759 

46.5 

1.4569 

56.5 

1.4636 

66.5 

1.4700 

76.5 

1.4762 

47.0 

1.4572 

57.0 

1.4639 

67.0 

1,4704 

77.0 

1.4765 

47.5 

1.4576 

57.5 

1.4642 

67.5 

1.4707 

77.5 

1.4768 

48.0 

1.4579 

58.0 

1.4646 

68.0 

1.4710 

78.0 

1.4771 

48.5 

1.4583 

58.5 

1.46^19 

68.5 

1.4713 

78.5 

1.4774 

49.0 

1.4586 

59.0 

1.4652 

69.0 

1.4717 

79.0 

1.4777 

49.5 

1.4590 

59.5 

1.4656 

69.5 

1.4720 

79.5 

1.4780 

MELTING  POINT  OF  FATS  AND  FATTY  ACIDS. 

Wiley  Method. — Official. 


Alcohol-water  mixture. — Specific  gravity  same  as  that  of  the  fat  to  be  examined. 
Prepare  by  boiling,  separately,  water  and  95%  alcohol  by  volume  for  10  minutes 
to  remove  the  gases  which  may  be  held  in  solution.  While  still  hot  pour  the  water 
into  the  test  tube  until  it  is  almost  half  full.  Nearly  fill  the  test  tube  with  the  hot 
alcohol,  poured  down  the  side  of  the  inclined  tube  to  avoid  too  much  mi.xing.  If 
the  alcohol  be  added  after  the  water  has  cooled,  the  mixture  will  contain  so  many 
air  bubbles  as  to  be  unfit  for  use. 


10  ,  DETERMINATION. 

Prepare  disks  of  fat  as  follows:  Allow  the  melted  and  filtered  fat  to  fall  a  distance 
of  15-20  cm.  from  a  dropping  tube  upon  a  piece  of  ice  or  upon  the  surface  of  cold 
mercury.     The  disks  thus  formed  should  be  1-1.5  cm.  in  diameter  and  weigh  about 


302  METHODS    OF   ANALYSIS  [Chap. 

200  mg.  When  solid  remove  the  disk  and  allow  to  stand  2-3  hours  in  order  to  obtain 
the  normal  melting  point. 

Place  a  test  tube,  30  by  3.5  cm.,  containing  the  alcohol-water  mixture,  in  a  tall 
beaker,  35  by  10  cm.,  containing  ice  and  water,  until  cold.  Then  drop  the  disk  of 
fat  into  the  tube  and  it  will  at  once  sink  to  a  point  where  the  density  of  the  alcohol- 
water  mixture  is  exactly  equivalent  to  its  own.  Lower  an  accurate  thermometer, 
which  can  be  read  to  0.1°C.,  into  the  test  tube  until  the  bulb  is  just  above  the  disk. 
In  order  to  secure  an  even  temperature  in  all  parts  of  the  alcohol-water  mixture 
around  the  disk,  stir  gently  with  the  thermometer.  Slowly  heat  the  water  in  the 
beaker,  constantly  stirring  it  by  means  of  an  air  blast  or  other  suitable  device. 

When  the  temperature  of  the  alcohol-water  mixture  rises  to  about  6°C.  below 
the  melting  point  of  the  fat,  the  disk  of  fat  begins  to  shrivel  and  gradually  rolls  up 
into  an  irregular  mass.  Lower  the  thermometer  until  the  fat  particle  is  even  with 
the  center  of  the  bulb.  Rotate  the  thermometer  bulb  gently  and  regulate  the 
temperature  so  that  about  10  minutes  for  the  increment  of  the  last  2°C.  are 
required.  As  soon  as  the  fat  mass  becomes  spherical,  read  the  thermometer. 
Remove  the  tube  from  the  bath  and  again  cool.  Place  in  the  bath  a  second  tube 
containing  the  alcohol-water  mixture.  The  test  tube  is  of  sufficiently  low  tempera- 
ture to  cool  the  bath  to  the  desired  point,  ice  water  having  been  used  for  cooling. 
After  the  first  or  preliminary  determination,  regulate  the  temperature  of  the  bath 
so  as  to  reach  a  maximum  of  about  1.5°C.  above  the  melting  point  of  the  fat  under 
examination. 

Do  not  allow  the  edge  of  the  disk  to  touch  the  sides  of  the  tube.  If  so,  make  a 
new  determination.  Run  triplicate  determinations  of  which  the  second  and  third 
results  should  agree  closely. 

1 1  Capillary  Tube  Method^. — Tentative. 

Draw  the  melted  fat  or  fatty  acids  into  a  thin-walled  capillary  tube.  Use  a 
column  of  fat  1-2  cm.  long,  according  to  the  length  of  the  thermometer  bulb.  Seal 
1  end  of  the  tube  and  cool  on  ice  12-15  hours.  Attach  the  capillary  tube  to  the  bulb 
of  an  accurate  thermometer,  graduated  to  0.2°C.,  immerse  in  a  large  test  tube  of 
water  surrounded  by  a  beaker  of  water  and  heat  very  slowly.  An  apparatus 
similar  to  that  indicated  in  Fig.  12  may  be  used.  The  temperature  at  which  the 
substance  becomes  transparent  is  taken  as  the  melting  point. 

TITER  TEST. 

Alcoholic  or  Aqueous  Sodium  Hydroxid  Method. — Tentative. 

12  APPARATUS. 

Standard  thermometer. — The  thermometer  must  have  a  zero  mark,  0.1°  gradua- 
tions between  10°-60°C.,  and  auxiliary  reservoirs  at  the  upper  end  and  between  the 
0°  and  the  10°  marks.  The  cavity  in  the  capillary  tube  between  the  0°  and  the 
10°  marks  must  be  at  least  1  cm.  below  the  10°  mark,  which  must  be  about  3-4  cm. 
above  the  bulb,  the  total  length  of  the  thermometer  being  about  38  cm.  The  bulb 
should  be  about  3  cm.  long  and  6  mm.  in  diameter.  The  stem  of  the  thermometer 
should  be  6  mm.  in  diameter  and  made  of  the  best  thermometer  tubing,  with  scale 
etched  on  the  stem,  the  graduation  to  be  clear  cut  and  distinct.  The  thermometer 
should  have  been  annealed  for  75  hours  at  450°C.,  and  the  bulb  should  be  of  Jena 
normal  16'"  glass,  moderately  thin,  so  that  the  thermometer  will  be  quick-acting. 


FATS   AND    OILS 


DETERMINATION. 


303 


XXIII] 
13 

Saponify  75  grams  of  the  sample  in  a  metal  dish  with  60  cc.  of  30%  sodium  hy- 
droxid  solution  (36°  Baum6)  and  75  cc.  of  95%  alcohol  by  volume  or  120  cc.  of 
water.  Evaporate  to  dryness  over  a  very  low  flame  or  on  an  iron  or  asbestos  plate, 
stirring  constantly.  Dissolve  the  dry  soap  in  a  liter  of  boiling  water  and,  if  alcohol 
has  been  used,  boil  for  40  minutes  to  remove  it,  adding  sufficient  water  to  replace 
that  lost  in  boiling.     Liberate  the  fatty  acids  by  adding  100  cc.  of  30%  sulphuric 


FIG.  12.    APPARATUS  FOR  THE  MELTING  POINT  DETERMINATION. 

acid  (25°  Baum6)  and  boil  until  they  form  a  clear,  transparent  layer.  AVash  with 
boiling  water  until  free  from  sulphuric  acid,  collect  in  a  small  beaker  and 
place  on  a  steam  bath  until  the  water  has  settled  and  the  fatty  acids  are  clear;  then 
decant  into  a  dry  beaker,  filter  while  hot  and  dry  20  minutes  at  100°C.  When 
dried,  cool  the  fatty  acids  to  15°-20°C.  above  the  expected  titer  and  transfer  to  the 
titer  tube,  25  by  100  mm.  (1  by  4  inches)  and  made  of  glass  about  1  mm.  in  thickness. 
Place  in  a  16  ounce  wide-mouthed  bottle  of  clear  glass,  70  by  150  mm.   (2.8  by  6 


304  METHODS    OF   ANALYSIS  [Chap. 

inches),  fitted  with  a  perforated  cork,  so  as  to  hold  the  tube  rigidly  when  in  position. 
Suspend  the  standard  thermometer  so  that  it  can  be  used  as  a  stirrer,  and  stir  the 
mass  slowly  until  the  mercury  remains  stationary  for  30  seconds.  Then  allow  the 
thermometer  to  hang  quietly,  with  the  bulb  in  the  center  of  the  mass,  and  observe 
the  rise  of  the  mercury  column.  The  highest  point  to  which  it  rises  is  regarded 
as  the  titer  of  the  fatty  acids. 

Test  the  fatty  acids  for  complete  saponification  as  follows: 

Place  3  cc.  in  a  test  tube  and  add  15  cc.  of  95%  alcohol  by  volume.  Bring  the 
mixture  to  a  boil  and  add  an  equal  volume  of  ammonium  hydroxid  (sp.  gr.  0.96). 
A  clear  solution  should  result.  The  titer  must  be  made  at  about  20°C.  for  all  fata 
having  a  titer  above  30°C.,  and  at  10°C.  below  the  titer  for  all  other  fats. 

14  Glycerol-Potassium  Hydroxid  Method. — Tentative. 

Heat  75  cc.  of  glycerol-potassium  hydroxid  solution  (25  grams  of  potassium  hy- 
droxid in  100  cc.  of  high-test  glycerol)  to  150°C.  in  an  800  cc.  beaker;  then  add  50  cc. 
of  the  oil  or  melted  fat,  previously  filtered  if  necessary  to  remove  foreign  substances. 
Saponification  often  takes  place  almost  immediately,  but  heating,  with  frequent 
stirring,  should  be  continued  for  15  minutes,  avoiding  a  temperature  much  above 
150°C.  When  the  saponification  is  complete,  as  indicated  by  the  perfectly  homo- 
geneous solution,  pour  the  soap  into  an  800  cc.  casserole  containing  about  500  cc. 
of  nearly  boiling  water,  add  carefully  50  cc.  of  30%  sulphuric  acid  and  heat  the 
solution,  with  frequent  stirring,  until  the  layer  of  fatty  acids  separates  out  perfectly 
clear.  Transfer  the  fatty  acids  to  a  tall  separatory  funnel,  wash  3-4  times  with 
boiling  water  to  remove  all  mineral  acids,  draw  the  fatty  acids  off  into  a  small 
beaker,  and  allow  to  stand  on  a  steam  bath  until  the  water  has  settled  out  and  the 
acids  are  clear.  Filter  into  a  dry  beaker  and  heat  to  150°C.  on  a  thin  asbestos  plate, 
stirring  continually  with  the  thermometer,  transfer  to  a  titer  tube,  fill  it  to  within 
2.5  cm.  of  the  top  and  take  the  titer  as  directed  in  13. 

lODIN  ABSORPTION  NUMBER. 

Hubl  Method.— Official. 

15  REAGENTS. 

(a)  Htibl's  iodin  solution. — Dissolve  26  grams  of  pure  iodin  in  500  cc.  of  95%  alco- 
hol by  volume.  Dissolve  30  grams  of  mercuric  chlorid  in  500  cc.  of  95%  alcohol 
by  volume.  Filter  the  latter  solution,  if  necessary,  and  mix  the  2  solutions.  Let 
the  mixed  solution  stand  12  hours  before  using.  The  solution  loses  strength  with 
age,  but  can  be  used  so  long  as  35  cc.  of  N/10  thiosulphate  are  equivalent  to  25  cc. 
of  the  iodin  solution. 

(b)  N/10  sodium  thiosulphate. — Standardize  this  solution  as  follows:  Place  in  a 
glass-stoppered  flask  20  cc.  of  the  N/10  potassium  dichromate  and  10  cc.  of  the  15% 
potassium  iodid  solution.  Add  5  cc.  of  strong  hydrochloric  acid.  Dilute  with  100 
cc.  of  water  and  allow  the  N/10  sodium  thiosulphate  to  flow  slowly  into  the  flask 
until  the  yellow  color  of  the  liquid  has  almost  disappeared,  add  a  few  drops  of  the 
starch  indicator  and,  with  constant  shaking,  continue  to  add  the  N/10  sodium  thio- 
sulphate until  the  blue  color  just  disappears. 

(C)  Starch  indicator. — Prepare  as  directed  under  VII,  3  (a). 

(d)  15%  potassium  iodid  solution. 

(e)  N/10  potassium  dichromate. — The  dichromate  solution  should  be  checked 
against  pure  iron. 


XXIII]  FATS   AND    OILS  305 

16  DETERMINATION. 

Weigh  about  0.500  gram  of  fat,  or  0.250  gram  of  oil  (0.100-0.200  gram  in  the  case 
of  drying  oils  which  have  a  very  high  absorbent  power),  into  a  500  cc.  glass-stoppered 
flask  or  bottle.  Dissolve  the  fat  or  oil  in  10  cc.  of  chloroform.  Add  30  cc.  of  the 
HiJbl  iodin  solution  in  the  case  of  fats,  or  40-50  cc.  in  the  case  of  oils.  Place  the 
bottle  in  a  dark  place  and  allow  to  stand  for  3  hours,  shaking  occasionally. 

This  time  must  be  adhered  to  closely  in  order  to  obtain  good  results.  The  time 
allowed  does  not  give  the  complete  iodin  absorption  power  of  an  oil  or  fat  and  can 
not  be  compared  with  determinations  in  which  6-12  hours  have  been  used.  It  gives 
very  satisfactory  comparative  results,  but  the  time  factor  must  be  closely  observed. 

The  excess  of  iodin  should  be  at  least  as  much  as  is  absorbed.  Add  20  cc.  of  the 
15%  potassium  iodid  solution,  shake  thoroughly  and  then  add  100  cc.  of  water,  wash- 
ing down  any  free  iodin  that  may  be  found  on  the  stopper.  Titrate  the  iodin  with 
the  N/10  sodium  thiosulphate,  adding  the  latter  gradually,  with  constant  shaking, 
until  the  yellow  color  of  the  solution  has  almost  disappeared.  Add  a  few  drops  of 
the  starch  indicator  and  continue  the  titration  until  the  blue  color  has  entirely 
disappeared.  Toward  the  end  of  the  titration,  stopper  the  bottle  and  shake  vio- 
lently, so  that  any  iodin  remaining  in  solution  in  the  chloroform  may  be  taken  up 
by  the  potassium  iodid  solution.  Conduct  2  blank  determinations  along  with  that 
on  the  sample.  The  number  of  cc.  of  the  N/10  sodium  thiosulphate  required  by  the 
blank  less  the  amount  used  in  the  determination  gives  the  thiosulphate  equivalent 
of  the  iodin  absorbed  by  the  fat  or  oil.  Ascertain  the  iodin  number  by  calculating 
the  per  cent  by  weight  of  iodin  absorbed. 

Haniis  Method. — Official. 

17  REAGENTS. 

Hanus'  iodin  solution. — Dissolve  13.2  grams  of  iodin  in  1  liter  of  glacial  acetic 
acid  (99.5%)  which  shows  no  reduction  with  dichromate  and  sulphuric  acid.  Add 
enough  bromin  to  double  the  halogen  content  as  determined  by  titration  (3  cc.  of 
bromin  are  about  the  proper  amount).  The  iodin  may  be  dissolved  by  heating 
but  the  solution  should  be  cold  when  the  bromin  is  added. 

A  convenient  way  to  prepare  the  Hanus  solution  is  as  follows:  Measure  825  cc. 
of  acetic  acid  which  has  shown  no  reduction  by  the  dichromate  test  and  dissolve  in 
it  13.615  grams  of  iodin  with  the  aid  of  heat.  Cool  and  titrate  25  cc.  of  this  solu- 
tion against  the  N/10  sodium  thiosulphate.  Add  3  cc.  of  bromin  to  200  cc.  of  acetic 
acid  and  titrate  5  cc.  of  the  solution  against  the  N/10  sodium  thiosulphate.  Cal- 
culate the  quantity  of  bromin  solution  required  exactly  to  double  the  halogen  con- 
tent of  the  remaining  800  cc.  of  iodin  solution  as  follows: 

A  =  p  in  which 

A  =  cc.  of  bromin  solution  required; 

B  =  800  X  the  thiosulphate  equivalent  of  1  cc.  of  iodin  solution; 

C  =  the  thiosulphate  equivalent  of  1  cc.  of  bromin  solution. 
Example:  136.15  grams  of  iodin  are  dissolved  in  S2.50  cc.  of  acetic  acid.  30  cc. 
of  bromin  are  dissolved  in  2000  cc.  of  acetic  acid.  Titrating  50  cc.  of  the  iodin 
solution  against  the  standard  thiosulphate  shows  that  1  cc.  of  the  iodin  solution 
equals  1.1  cc.  of  the  thiosulphate  (0.01G5  gram  of  iodin).  Titrating  5  cc.  of  the  bro- 
min solution  shows  that  1  cc.  of  the  bromin  solution  equals  4.6  cc.  of  the  thiosulphate. 
Then  the  quantity  of  bromin  solution  required  to  double  the  halogen  content  of 

8200  X  1  1 
the  remaining  8200  cc.  of  iodin  solution  is  equivalent  to .  „ — '—  or  1961  cc.  Upon 


306  METHODS    OF   ANALYSIS  [Chap. 

mixing  the  2  solutions  in  this  proportion,  a  total  volume  of  10161  cc  is  obtained, 
containing  135.3  grams  of  iodin.  In  order  to  reduce  this  solution  to  the  proper 
strength  (13.2  grams  iodin  per  liter),  10.161X13.2  =  134.1;  135.3-  134.1  =  1.2] 


1  2  X  1000 
of  iodin  present  in  excess,  or  —  =  91  cc.  of  acetic  acid  which  must  be  added. 

The  other  reagents  used  are  described  under  15. 

18  DETERMINATION. 

Weigh  about  0.500  gram  of  fat,  or  0.250  gram  of  oil  (0.100-0.200  gram  in  the  case 
of  drying  oils  which  have  a  very  high  absorbent  power),  into  a  500  cc.  glass-stoppered 
flask  or  bottle.  Dissolve  the  fat,  or  oil,  in  10  cc.  of  chloroform,  add  25  cc.  of  the 
Hanus  iodin  solution  and  allow  to  stand  for  30  minutes,  shaking  occasionally, 
The  excess  of  iodin  should  be  at  least  60%  of  the  amount  added.  Add  10  cc.  of  the 
15%  potassium  iodid  solution  and  continue  as  directed  under  16. 

SAPONIFICATION  NUMBER  (KOETTSTORFER  NUMBER).-OFFICIAL. 

1  REAGENTS. 

(a)  N 1%  hydrochloric  acid. — Prepare  as  directed  under  I,  16  (a). 

(b)  Alcoholic  potassium  hijdroxid  solution. — Dissolve  40  grams  of  the  purest 
potassium  hydroxid  in  1  liter  of  95%  redistilled  alcohol  by  volume.  The  alcohol 
should  be  redistilled  from  potassium  hydroxid  over  which  it  has  been  standing  for 
some  time,  or  with  which  it  has  been  boiled  for  some  time  using  a  reflux  condenser. 
The  solution  must  be  clear  and  the  potassium  hydroxid  free  from  carbonates. 

20  DETERMINATION. 

Weigh  accurately  about  5  grams  of  the  filtered  sample  into  a  250-300  cc.  Erlen- 
meyer  flask.  Pipette  50  cc.  of  the  alcoholic  potassium  hydro.xid  solution  into  the 
flask,  allowing  the  pipette  to  drain  for  a  definite  time.  Connect  the  flask  with  an 
air  condenser  and  boil  until  the  fat  is  completely  saponified  (about  30  minutes). 
Cool  and  titrate  with  the  N/2  hydrochloric  acid,  using  phenolphthalein  as  an  indi- 
cator. Calculate  the  Koettstorfer  number  (mg.  of  potassium  hydroxid  required  to 
saponify  1  gram  of  fat).  Conduct  2  or  3  blank  determinations,  using  the  same 
pipette  and  draining  for  the  same  length  of  time  as  above. 

21  SOLUBLE  ACIDS.-OFFICIAL. 

Place  the  flask,  used  in  20,  on  a  water  bath  and  evaporate  the  alcohol.  Add  such 
an  amount  of  N/2  hydrochloric  acid  that  its  volume  plus  the  amount  used  in  titrat- 
ing for  the  saponification  number  will  be  1  cc.  in  excess  of  the  amount  required  to 
neutralize  the  50  cc.  of  the  alcoholic  potassium  hydroxid  solution  added,  and  place 
on  the  steam  bath  until  the  separated  fatty  acids  form  a  clear  layer  on  the  upper 
surface  of  the  liquid.  Fill  to  the  neck  with  hot  water  and  cool  in  ice  water  until 
the  cake  of  fatty  acids  is  thoroughly  hardened.  Pour  the  liquid  contents  of  the 
flask  through  a  filter  into  a  liter  flask.  Fill  the  flask  again  with  hot  water,  set  on 
the  steam  bath  until  the  fatty  acids  collect  at  the  surface,  cool  by  immersing  in  ice 
water,  and  again  filter  the  liquid  into  the  liter  flask.  Repeat  this  treatment  with 
hot  water  3  times,  cooling  and  collecting  the  washings  in  the  liter  flask  after  each 
treatment.  Titrate  the  combined  washings  with  N/10  alkali,  using  phenolphthalein 
as  an  indicator.  Subtract  5  (corresponding  to  the  excess  of  1  cc.  of  N/2  acid)  from 
the  number  of  cc.  of  N/10  alkali  used  and  multiply  by  0.0088  to  obtain  the  weight 
of  soluble  acids  as  butyric  acid.     Calculate  the  percentage  of  soluble  acids. 


XXIII]  FATS   AND    OILS  307 

22  INSOLUBLE  ACIDS  (HEHNER  NUMBER).-OFFICIAL. 

Allow  the  flask,  containing  the  cake  of  insoluble  fatty  acids  from  21  and  the 
paper  throu<fh  which  the  soluble  fatty  acids  have  been  filtered,  to  drain  and  dry 
for  12  hours.  Transfer  the  cake,  together  with  as  much  of  the  fatty  acids  as  can 
be  removed  from  the  filter  paper,  to  a  weighed,  wide-mouthed  beaker  flask.  Then 
place  the  funnel,  containing  the  filter,  in  the  neck  of  the  flask  and  wash  the  paper 
thoroughly  with  hot  absolute  alcohol.  Remove  the  funnel,  evaporate  off  the  alco- 
hol, dry  for  2  hours  at  100°C.,  cool  in  a  desiccator  and  weigh.  Again  dry  for  2  hours, 
cool  and  weigh.  If  there  is  any  considerable  decrease  in  weight,  re-heat  for  2  hours 
and  weigh  again.     Calculate  the  percentage  of  insoluble  fatty  acids. 

SOLUBLE  VOLATILE  ACIDS  (REICHERT-MEISSL  NUMBER). 

(As  these  determinations  are  entirely  empirical,  the  directions  given  must  be 
followed  exactly.     In  reporting  results  the  method  used  should  always  be  stated.) 

Reicheri-Meissl  Method. — Official. 

23  REAGENTS. 

(a)  Sodium  hydroxid  solution  (1  to  1). — The  sodiimi  hydroxid  should  be  as  free  as 
possible  from  carbonates.  Protect  the  solution  from  contact  with  carbon  dioxid. 
Allow  to  settle  and  use  only  the  clear  liquid. 

(b)  Potassium  hydroxid  solution. — Dissolve  100  grams  of  the  purest  potassium 
hydroxid  in  oS  cc.  of  hot  water.  Cool  in  a  stoppered  vessel,  decant  the  clear  solu- 
tion and  protect  from  contact  with  carbon  dioxid. 

(C)  55%  alcohol  by  volume. — Distilled  over  sodium  hydroxid. 

(d)  Dilute  sulphuric  acid. — Dilute  200  cc.  of  the  strongest  acid  to  1  liter  with 
water. 

(e)  Barium  {or  sodium)  hydroxid  solution. — Standardize  an  approximately  N/10 
solution. 

(f )  Indicator. — Dissolve  1  gram  of  phenolphthalein  in  100  cc.  of  95%  alcohol. 

(^)  Pumice  stone. — Heat  small  pieces  to  a  white  heat,  plunge  in  water,  and  keep 
under  water  until  used. 

24  SAPONIFICATION. 

Weigh  5.75  cc,  about  5  grams,  of  the  filtered  sample,  into  a  saponification  flask 
and  proceed  by  1  of  the  following  3  methods. 

(1)  Under  pressure  with  alcohol. — Place  10  cc.  of  the  95%  alcohol  in  the  flask 
containing  the  fat  (the  flask  must  be  made  of  strong,  well-annealed  glass,  capable 
of  resisting  the  tension  of  alcoholic  vapor  at  100°C.)  and  add  2  cc.  of  the  sodium 
hydroxid  solution.  Insert  a  soft,  cork  stopper  into  the  neck  of  the  flask,  tie  down 
and  place  the  stoppered  flask  on  a  water  or  steam  bath  for  at  least  an  hour, 
rotating  the  flask  gently  from  time  to  time.     Cool  before  opening. 

(2)  Under  pressure  without  the  use  of  alcohol. — Place  2  cc.  of  the  potassium  hy- 
droxid solution  in  the  flask  containing  the  fat  (the  flask  being  round-bottomed  and 
made  of  well-annealed  glass  to  resist  pressure),  cork  and  heat  as  directed  under 
(1).  This  method  avoids  the  formation  of  esters  and  the  removal  of  the  alcohol 
after  saponification. 

(3)  With  a  reflux  condenser  and  the  use  of  alcohol. — Place  10  cc.  of  the  95%  alcohol 
in  the  flask  containing  the  fat,  add  2  cc.  of  the  sodium  hydroxid  solution  and  heat  on 
a  steam  bath  until  the  saponification  is  complete,  using  a  reflux  condenser. 

After  the  saponification,  if  alcohol  was  used,  remove  it  by  evaporation  on  a 
steam  bath. 


308  METHODS    OF   ANALYSIS  [Chap. 

25  DISTILLATION   AND   TITRATION. 

Dissolve  the  soap,  obtained  as  directed  under  24,  by  adding  135  cc.  of  recently 
boiled  water  (132  cc.  if  potassium  hydroxid  was  used  in  the  saponification)  and  warm 
on  the  water  bath,  with  occasional  shaking,  until  the  solution  is  clear.  Cool  to 
60°-70°C.,  add  5  cc.  of  the  dilute  sulphuric  acid  (8  cc.  if  potassium  hydroxid  was 
used  in  the  saponification),  stopper  loosely  and  heat  on  the  water  bath  until  the 
fatty  acids  form  a  clear,  transparent  layer.  Cool  to  room  temperature,  add  a  few 
pieces  of  the  pumice  stone  and  connect  with  a  glass  condenser  by  means  of  a  bulb 
tube.  Heat  slowly  with  a  free  flame  until  ebuUition  begins  and  distil,  regulating 
the  {lame  so  as  to  collect  110  cc.  of  distillate  in  as  nearly  30  minutes  as  possible. 
Mix  this  distillate,  filter  through  a  dry  filter,  and  titrate  100  cc.  with  the  standard 
barium  or  sodium  hydroxid  solution,  using  phenolphthalein  as  an  indicator.  The 
red  color  should  remain  unchanged  for  2-3  minutes. 

Multiply  the  number  of  cc.  of  N/10  alkali  used  by  1.1,  divide  by  the  weight 
of  fat  taken  and  multiply  by  5  to  obtain  the  Reichert-Meissl  number.  Correct  the 
result  by  the  figure  obtained  in  a  blank  determination. 

Leffman  and  Beam  Method. — Official. 

26  REAGENTS. 

Glycerol-soda  solution. — Add  20  cc.  of  the  sodium  hydroxid  solution,  prepared  as 
directed  under  23  (a),  to  180  cc.  of  pure,  concentrated  glycerol. 
The  other  reagents  used  are  described  under  23. 

27  DETERMINATION. 

Add  20  cc.  of  the  glycerol-soda  solution  to  about  5  grams  of  the  fat  in  a  flask, 
weighed  as  directed  under  24,  and  heat  over  a  free  flame,  or  on  an  asbestos  plate, 
until  complete  saponification  takes  place,  as  shown  by  the  mixture  becoming 
perfectly  clear.     If  foaming  occurs,  shake  the  flask  gently. 

Add  135  cc.  of  recently  boiled  water,  drop  by  drop  at  first,  to  prevent  foaming, 
and  5  cc.  of  the  dilute  sulphuric  acid,  distil  without  previous  melting  of  the  fatty 
acids,  using  an  apparatus  similar  to  that  illustrated  in  28,  Fig.  13,  regulating  the 
flame  so  as  to  collect  110  cc.  of  distillate  in  as  nearly  30  minutes  as  possible.  Filter, 
titrate  the  volatile  acids  and  calculate  the  Reichert-Meissl  number,  as  directed 
under  25.     Conduct  a  blank  determination  and  correct  the  result  accordingly. 

INSOLUBLE  VOLATILE  ACIDS   (POLENSKE  NUMBER). 

28  Polenske  Method^. — Tentative. 

Proceed  as  directed  under  27  up  to  the  point  at  which  110  cc.  of  distillate  have 
been  collected,  except  that  only  20  minutes  are  allowed  for  the  distillation,  em- 
ploying an  apparatus  of  the  exact  dimensions  illustrated  in  Fig.  13.  Substitute  a 
25  cc.  cylinder  for  the  receiving  fla^sk  to  collect  any  drops  that  may  fall  after  the 
flame  has  been  removed.  Immerse  the  flask  containing  the  distillate  almost  com- 
pletely in  water  at  15°C.  for  15  minutes,  filter  the  UOcc.  of  distillate  and  determine 
the  approximate  Reichert-Meissl  number,  if  desired,  as  in  27,  avoiding  too  violent 
shaking  of  the  distillate  and  consequent  emulsification  of  the  insoluble  acids  pre- 
vious to  filtration.  Remove  the  remainder  of  the  soluble  acids  from  the  insoluble 
acids  upon  the  filter  paper  by  washing  with  3  successive  portions  of  15  cc.  of  water, 
previously  passed  through  the  condenser,  the  25  cc.  cylinder  and  the  110  cc.  receiv- 
ing flask.     Then  dissolve  the  insoluble  acids  by  passing  3  successive  15  cc.  por- 


xxin] 


FATS   AND    OILS 


309 


tions  of  neutral  90%  alcohol  by  volume  through  the  filter,  each  portion  previously- 
passed  through  the  condenser,  the  25  cc.  cylinder  and  the  110  cc.  receiving  flask. 
Titrate  the  combined  alcoholic  washings  with  N/10  sodium  hydroxid,  using  phenol- 
phthalein  as  an  indicator. 

Run  a  blank  in  the  same  manner  and  subtract  the  quantity  of  the  standard  alkali 
required  to  neutralize  the  45  cc.  of  alcohol,  used  in  washing  the  apparatus  and  filter 
paper  of  the  blank,  from  that  required  in  each  Polenske  determination.  Report 
the  Polenske  number  as  the  number  of  cc.  of  N/10  alkali  required  to  neutralize  the 
insoluble  volatile  acids  from  the  110  cc.  of  distillate  as  obtained  above.  Since  the 
entire  distillate  is  filtered  it  is  not  necessaiy  to  multiply  the  burette  reading  by  1.1, 
as  in  25,  but  a  calculation  must  be  made,  as  directed  in  25,  to  reduce  the  actual 
number  of  cc.  found  in  the  titration  to  the  number  which  would  have  been  required 
had  exactly  5  grams  of  fat  been  used. 


FIG.  13.    APPARATUS'  FOR  THE  DETERMINATION  OF  THE  POLENSKE  NUMBER. 


29 


LIQUID  AND  SOLID  FATTY  ACIDS. 
Muter  Method,  Modified  hy  Lane^. — Tentative. 


Weigh  5  grams  of  the  oil  or  fat  into  an  Erlenmeyer  flask,  saponify,  precipitate  with 
lead  acetate  solution  and  treat  the  precipitated  lead  soap  with  ether,  as  directed 
under  37.  Filter  the  ether  solution  of  the  soluble  lead  soap  into  a  Muter  tube  or 
separatory  funnel  and  decompose  the  soap  by  shaking  with  40  cc.  of  hydrochloric 
acid  (1  to  5).  The  soap  is  completely  decomposed  when  the  ether  becomes  clear 
and  colorless. 

Draw  off  the  lead  chlorid  from  the  ether  solution  and  wash  the  ether  free  from 
acid.  Evaporate,  until  free  from  ether,  an  aliquot  of  this  solution  in  an  atmosphere 
of  carbon  dioxid,  in  order  t!o  prevent  the  oxidation  of  the  oleic  acid,  and  weigh  to 
determine  the  per  cent  of  liquid  acids;  determine  the  iodin  number  as  directed  in 
16  or  18,  using  0.2-0.3  gram  of  this  residue. 


310  METHODS    OF   ANALYSIS  [Chap. 

As  it  is  very  difficult  to  dry  the  unsaturated  acids  without  very  serious  oxidation, 
it  is  just  as  satisfactory  to  determine  the  weight  of  insoluble  acids  by  the  following 
method: 

Wash  the  insoluble  soap  left  on  the  filter  into  a  flask,  decompose  with  hydro- 
chloric acid  and  heat  until  the  fatty  acids  are  melted.  Fill  the  flask  with  hot  water, 
cool,  pour  off  the  water  and  again  wash  the  solidified  fatty  acids.  Dissolve  in  hot 
95%  alcohol  by  volume,  transfer  to  a  weighed  dish,  remove  the  alcohol  by  evapo- 
ration, dry,  weigh  and  calculate  the  percent  of  solid  fatty  acids. 

30  FREE  FATTY  ACIDS.— OFFICIAL. 

Weigh  20  grams  of  fat,  or  oil,  into  a  flask,  add  50  cc.  of  95%  alcohol  by  volume 
which  has  been  neutralized  with  dilute  sodium  hydroxid  solution,  using  phenol- 
phthalein  as  an  indicator,  and  heat  to  boiling.  Shake  the  flask  thoroughly  in  order 
to  dissolve  the  free  fatty  acids  as  completely  as  possible.  Titrate  with  N/10  alkali, 
shaking  thoroughly  until  the  pink  color  persists  after  vigorous  shaking. 

Express  the  results  either  as  percentage  of  oleic  acid,  as  acid  degree  (cc.  of  N/1 
alkali  required  to  neutralize  the  free  acids  in  100  grams  of  oil  or  fat),  or  as  acid 
value  (mg.  of  potassium  hydroxid  required  to  saturate  the  free  acids  in  1  gram  of  fat 
or  oil). 

One  cc.  of  N/10  alkali  is  equivalent  to  0.0282  gram  of  oleic  acid. 

ACETYL  VALUE. 

31  Benedikt-Leiokoioitsch  Method^. — Tentative. 

Boil  the  oil  or  fat  with  an  equal  volume  of  acetic  anhydrid  for  2  hours,  pour  the 
mixture  into  a  large  beaker  containing  500  cc.  of  water  and  boil  for  30  minutes. 
To  prevent  bumping,  pass  a  slow  current  of  carbon  dioxid  into  the  liquid  through  a 
finely  drawn  out  tube  reaching  nearly  to  the  bottom.  Allow  the  mixture  to  sepa- 
rate into  2  layers,  siphon  off  the  water,  and  boil  the  oily  layer  with  fresh  water 
until  it  is  no  longer  acid  to  litmus  paper.  Separate  the  acetylated  fat  from  the  water 
and  drj^  and  filter  in  a  drying  oven. 

Weigh  2-4  grams  of  the  acetylated  fats  into  a  flask  and  saponify  with  alcoholic 
potash  as  in  20.  If  the  distillation  process  is  to  be  adopted,  it  is  not  necessary  to 
work  with  a  standardized  alcoholic  potassium  hydroxid  solution,  but  in  the  fil- 
tration method,  which  is  much  shorter,  the  alcoholic  potassium  hydroxid  solution 
must  be  measured  exactly.  In  either  case  evaporate  the  alcohol  after  saponification 
and  dissolve  the  soap  in  water.     Then  either  distil  or  filter  as  follows: 

(1)  Distillation. — Acidify  with  sulphuric  acid  (1  to  10)  and  distil  as  in  25.  As 
several  hundred  cc.  must  be  distilled,  either  run  a  current  of  steam  through  or  add 
portions  of  water  from  time  to  time  (500-700  cc.  of  distillate  will  be  sufficient). 
Filter  the  distillates  to  remove  any  insoluble  acids  carried  over  by  the  steam  and 
titrate  with  N/10  potassium  hydro.xid,  using  phenolphthalein  as  an  indicator.  Mul- 
tiply the  nmnber  of  cc.  of  alkali  employed  by  5.61  and  di^dde  by  the  weight  of  sub- 
stance used  to  obtain  the  acetyl  value. 

(2)  Filtration. — Add  to  the  soap  solution  a  quantity  of  standard  sulphuric  acid 
exactly  corresponding  to  the  amount  of  alcoholic  potassium  hydroxid  solution 
added,  warm  gently,  filter  off  the  free  fatty  acids  which  collect  on  top,  wash  with 
boiling  water  until  the  washings  are  no  longer  acid  and  titrate  the  filtrate  with  N/10 
potassium  hydroxid,  using  phenolphthalein  as  an  indicator.  Calculate  the  acetyl 
value  as  directed  under  (1). 


XXIII]  FATS   AND    OILS  311 

CHOLESTEROL  AND  PHYTOSTEROL  IN  MIXTURES  OF  ANIMAL  AND  VEGETABLE  FATS. 
32  Alcohol  Extraction  Method^°. — Tentative. 

Introduce  200-300  grams  of  the  melted  fat  into  a  fiat-bottomed  liter  flask.  Close 
the  neck  of  the  flask  with  a  3-holed  stopper  and  insert  through  these  holes:  (1)  a 
reflux  condenser;  (2)  a  right-angled  glass  tube,  one  arm  of  which  reaches  to  a  point 
6  mm.  above  the  surface  of  the  melted  fat,  the  other  being  closed  a  short  distance 
from  the  flask  by  means  of  a  short  piece  of  rubber  tubing  and  a  pinch-cock;  (3)  a 
glass  tube  bent  so  that  one  arm  reaches  down  to  the  bottom  of  the  flask  and  the 
other  serves  as  a  delivery  tube  for  a  700  cc.  round-bottomed  flask  containing  500  cc. 
of  95%  alcohol  by  volume. 

Place  the  flasks,  containing  the  melted  fat  and  the  alcohol,  on  a  steam  bath  and 
heat  so  that  the  alcohol  vapor  passes  through  the  melted  fat  in  the  liter  flask  and 
is  condensed  in  the  reflux  condenser,  finally  collecting  in  a  layer  over  the  melted 
fat.  After  all  the  alcohol  has  passed  in  this  manner  into  the  flask  containing  the 
fat,  disconnect  the  flask  from  which  the  alcohol  has  been  distilled  and  attach  a 
tube  to  the  short  piece  of  rubber  tubing  attached  to  the  right-angled  glass  tube 
[see  (2)  above]  and  siphon  the  alcohol  layer  back  into  the  alcohol  distillation  flask. 
Reconnect  as  at  first  and  again  distil  the  alcohol  as  in  the  first  operation.  When 
all  the  alcohol  has  been  distilled,  siphon  it  again  into  the  distillation  flask  and 
extract  in  the  same  manner  for  a  third  time. 

Discard  the  fat  and  retain  the  alcohol  which  now  contains  practically  all  of  the 
cholesterol  and  phytosterol  originally  present  in  the  fat.  Concentrate  the  alcoholic 
solution  to  about  250  cc.  and  add  20  cc.  of  potassium  hydroxid  solution  (1  to  1) 
to  the  boiling  liquid.  Boil  for  10  minutes  to  insure  complete  saponification  of  the 
fat,  cool  to  room  temperature  and  pour  into  a  large  separatory  funnel  containing 
500  cc.  of  warm  ether.  Shake  to  insure  thorough  mixing  and  add  500  cc.  of  water. 
Rotate  the  funnel  gently  to  avoid  the  formation  of  e.xtremely  stubborn  emulsions, 
but  mix  the  water  thoroughly  with  the  alcohol-ether-soap  solution.  A  clear,  sharp 
separation  takes  place  at  once.  Draw  off  the  soap  solution  and  wash  the  ether  layer 
with  300  cc.  of  water,  avoiding  shaking.  Repeat  the  washing  of  the  ether  solution 
with  small  quantities  of  water  until  all  the  soap  is  removed.  Transfer  the  ether 
layer  to  a  flask  and  distil  the  ether  until  the  volume  of  liquid  remaining  in  the 
flask  measures  about  25  cc.  Transfer  this  residue  to  a  tall  50  cc.  beaker  and 
continue  the  evaporation  until  all  the  ether  is  driven  off  and  the  residue  is  per- 
fectly dry.  If  desired,  a  tared  beaker  may  be  used  and  the  weight  of  the  unsaponi- 
fiable  matter  determined  at  this  point. 

Add  3-5  cc.  of  acetic  anhydrid  to  the  residue  in  the  beaker,  cover  the  beaker 
with  a  watch  glass  and  heat  to  boiling  over  a  free  flame.  After  boiling  for  a  few 
seconds,  remove  the  beaker  from  the  flame,  cool  and  add  35  cc.  of  60%  alcohol  by 
volume.  Mix  the  contents  of  the  beaker  thoroughly,  filter  off  the  alcoholic  solution 
and  wash  the  precipitate  with  60%  alcohol.  Dissolve  the  precipitate  on  the  filter 
with  a  stream  of  hot  80%  alcohol  by  volume  and  wash  the  insoluble  portion  well 
with  80%  alcohol.  Acetates  of  cholesterol  and  phytosterol  are  dissolved  while  the 
greater  i)ortion  of  the  impurities  present  (including  paraffin  and  paraffin  oil  if  pres- 
ent) remain  behind  on  the  filter.  Cool  the  combined  filtrate  and  washings  to  a 
temperature  of  10°-12°C.  and  allow  to  stand  at  that  temperature  for  2-3  hours. 
During  this  time  the  acetates  of  cholesterol  and  phytosterol  crystallize  from  the 
solution.  Collect  the  crystals  upon  a  filter,  wash  with  cold  80%  alcohol  and  then 
dissolve  them  in  a  minimum  amount  of  hot  absolute  alcohol.  Collect  the  alcoholic 
solution  of  the  acetates  in  a  small,  glass  evaporating  dish,  add  2  or  3  drops  of  water 
to  the  solution  and  heat  if  not  perfectly  clear.     Allow  the  alcohol  to  evaporate 


312  METHODS    OF   ANALYSIS  [Chap. 

spontaneously,  the  contents  of  the  dish  being  stirred  occasionally  to  mix  the  deposit 
of  crj-stals,  which  form  upon  the  edges,  with  the  main  body  of  the  liquid.  As  soon 
as  a  good  deposit  of  crystals  has  formed,  collect  them  upon  a  hardened  filter,  wash 
twice  with  cold  90%  alcohol  and  dry  by  suction,  drying  finally  at  100°C.  for  30  min- 
utes, and  determine  the  melting  point  in  the  apparatus  shown  in  1 1 ,  Fig.  12,  using 
sulphuric  acid  in  the  outer  beaker  and  glycerin  in  the  inner  tube. 

The  melting  point  of  the  first  crop  of  crystals  usually  gives  definite  information 
as  to  the  presence  or  absence  of  phytosterol  but  the  conclusion  indicated  should  be 
confirmed  by  recrystallizing  the  crystals  from  absolute  alcohol  and  again  determin- 
ing the  melting  point.  If  the  crystals  are  pure  cholesteryl  acetate,  the  melting  point 
of  the  second  crop  should  agree  closely  with  that  of  the  first.  If  phytosteryl  acetate 
is  present,  however,  a  higher  melting  point  will  be  noted,  as  phytosteryl  acetate  is 
less  soluble  in  alcohol  than  cholesteryl  acetate.  The  melting  point  of  cholesteryl 
acetate  is  114°C.,  that  of  phytosteryl  acetate  125°-137°C. 

33  Digitonin  Method.    (Marcusson  and  Schilling^^) — Tentative. 

Shake  vigorously  50  grams  of  the  oil  or  fat  for  15  minutes  in  a  separatory  funnel 
with  20  cc.  of  a  1%  solution  of  digitonin  in  95%  alcohol  by  volume.  Allow  the 
mixtm-e  to  stand  for  a  time  until  the  emulsion  separates.  The  lower  or  fat  layer 
should  be  quite  clear  while  the  alcohol  layer  contains  a  bulky,  flocculent  precipitate. 
Draw  off  as  much  as  possible  of  the  fat,  avoiding  any  loss  of  the  precipitate.  Add 
100  cc.  of  ether  to  the  alcohol  layer  and  filter  the  mixture.  Wash  the  precipitate 
with  ether  until  free  from  fat;  after  drying  in  the  air,  transfer  it  to  a  tall  50  cc. 
beaker,  add  2-3  cc.  of  acetic  anhydrid  and  cover  the  beaker  with  a  watch  glass. 
Then  boil  slowly  over  a  low  flame  for  30  minutes.  After  cooling,  add  30-35  cc.  of 
60%  alcohol  by  volume  and  mix  the  contents  of  the  beaker  thoroughly.  Filter 
off  the  alcohol  solution  and  wash  the  precipitate  with  60%  alcohol,  then  dissolve  it 
on  the  filter  with  a  stream  of  hot  80%  alcohol  by  volume  from  a  wash  bottle  and 
set  aside  the  filtrate  in  a  cool  place  (10°C.  or  below).  After  the  acetates  have 
crystallized  out  of  this  solution  filter  them  off,  recrj'stallize  from  absolute  alcohol, 
dry  and  determine  the  melting  point  of  each  crop  of  crystals,  as  directed  under  32. 

34  UNSAPONIFIABLE  RESIDDEi^.-TENTATIVE. 

Saponify  5  grams  of  the  oil  or  fat  with  alcoholic  potassium  hydroxid  solution  and 
remove  the  alcohol  by  evaporation.  Wash  into  a  separatory  funnel  with  70-100  cc. 
of  water  and  extract  with  50-60  cc.  of  ether.  If  the  2  liquids  do  not  separate,  add  a 
few  cc.  of  alcohol.  Separate  the  water  solution  and  wash  the  ether  with  water  con- 
taining a  few  drops  of  sodium  hydroxid  solution.  Again  extract  the  soap  solution 
and  washings  with  ether  and  evaporate  the  combined  extracts  to  dryness.  In  most 
cases  it  is  advisable  to  add  a  little  alcoholic  potassium  hydroxid  solution  to  the 
residue  and  heat  in  order  to  saponify  any  traces  of  fats  left  unsaponified  and  extract 
again  with  ether.  Transfer  to  a  weighed  dish  and  dry  as  quickly  as  possible  in  a 
water  oven. 

Many  of  the  hydrocarbon  oils  are  volatile  at  100°C.,  so  that  the  drying  should 
not  be  carried  any  further  than  necessary.  With  resin  oil,  paraffin  wax  and  the 
denser  mineral  oils  there  is  little  danger  of  loss  at  100°C. 

On  account  of  the  solubility  of  soap  in  ether  and  petrolemn  ether  it  is  well  to 
wash  the  residue  with  warm  water  containing  a  little  phenolphthalein.  If  the 
reaction  is  alkaline,  soap  is  present  and  the  residue  must  be  further  purified. 


XXIII]  TATS    AND    OILS  313 

RESIN  OIL, 

35  Qualitative  Test. — Tentative. 

Polarize  the  pure  oil,  or  a  definite  dilution  with  petroleum  ether,  in  a  200  mm. 
tube.  Resin  oil  has  a  polarization  in  a  200  mm.  tube  of  from  +  30°  to  +  40°  on  the 
sugar  scale  (Schmidt  and  Haensch)  while  most  oils"  read  between  +  1°  and  —1°. 

COTTONSEED  OIL. 

36  Halphen  TesV*.— Official. 

Mix  carbon  disulphid,  containing  about  1%  of  sulphur  in  solution,  with  an  equal 
volume  of  amyl  alcohol.  Mi.x  equal  volumes  of  this  reagent  and  the  oil  under  ex- 
amination, and  heat  in  a  bath  of  boiling,  saturated  brine  for  1-2  hours.  In  the 
presence  of  as  little  as  1%  of  cottonseed  oil,  a  characteristic  red  or  orange-red  color 
is  produced. 

Lard  and  lard  oil  from  animals  fed  on  cottonseed  meal  will  give  a  faint  reaction; 
their  fatty  acids  also  give  this  reaction. 

The  depth  of  color  is  proportional,  to  a  certain  extent,  to  the  amount  of  oil  pres- 
ent, and  by  making  comparative  tests  with  cottonseed  oil  some  idea  as  to  the 
amount  present  can  be  obtained.  Different  oi's  react  with  different  intensities,  and 
oils  which  have  been  heated  from  200°-210°C.i5  react  with  greatly  diminished  in- 
tensity. Heating  10  minutes  at  250°C.  renders  cottonseed  oil  incapable  of  giving 
the  reaction^^. 

PEANUT  OIL. 

37  Modified  Renard  Tesl^^. —Tentative. 

Weigh  20  grams  of  the  oil  into  an  Erlenmeyer  flask.  Saponify  with  alcoholic 
potash  solution,  neutralize  exactly  with  dilute  acetic  acid,  using  phenolphthalein 
as  an  indicator,  and  wash  into  an  800-1000  cc.  flask  containing  a  boiling  mixture  of 
100  cc.  of  water  and  120  cc.  of  20%  lead  acetate  solution.  Boil  for  a  minute  and 
then  cool  the  precipitated  soap  by  immersing  the  flask  in  water,  occasionally 
giving  it  a  whirling  motion  to  cause  the  soap  to  stick  to  the  sides  of  the  flask.  After 
the  flask  has  cooled,  decant  the  water  and  excess  of  lead  acetate  solution  and  wash 
the  lead  soap  with  cold  water  and  90%  alcohol  by  volume.  Add  200  cc.  of  ether, 
cork  and  allow  to  stand  for  some  time  until  the  soap  is  disintegrated;  heat  on  a 
water  bath,  using  a  reflux  condenser,  and  boil  for  about  5  minutes'*.  In  the  case  of 
oils,  most  of  the  soap  will  be  dissolved,  while  in  lards,  which  contain  much  stearin, 
part  of  the  soap  will  be  left  undissolved.  Cool  the  ether  solution  of  soap  to  15°- 
17°C.  and  allow  to  stand  until  all  the  insoluble  soaps  have  separated  out  (about  12 
hours). 

Filter  upon  a  Biichner  funnel  and  thoroughly  wash  the  insoluble  lead  soaps 
with  ether.  Wash  the  ether-insoluble  lead  soaps  into  a  scparatory  funnel  by  means 
of  a  jet  of  ether,  alternating  at  the  end  of  the  operation,  if  a  little  of  the  soap  sticks 
to  the  paper,  with  hydrochloric  acid  (1  to  3).  Add  sufficient  hydrochloric  acid  (1  to  3) 
so  that  the  total  volume  of  the  latter  amounts  to  about  200  cc.  and  enough  ether  to  make 
the  total  volume  of  it  1.50-200  cc.  and  shake  vigorously  for  several  minutes.  Allow  the 
layers  to  separate,  run  off  the  acid  layer,  and  wash  the  ether  once  with  100  cc.  of  dilute 
hydrochloric  acid  and  then  with  several  portions  of  water  until  the  water  washings 
are  no  longer  acid  to  me^^hyl  orange.  If  a  few  undecomposed  lumps  of  lead  soap  re- 
main (indicated  by  solid  particles  remaining  after  the  third  washing  with  water), 
break  these  up  bj'  running  off  almost  all  the  water  layer  and  then  a  add  little  concen- 
trated hydrochloric  acid,  shake  and  then  continue  the  washing  with  water  as  before. 


314  METHODS   OF  ANALYSIS  [Chap. 

Distil  the  ether  from  the  solution  of  insoluble  fatty  acids  and  dry  the  latter  in  the 
flask  by  adding  a  little  absolute  alcohol  and  evaporating  on  a  steam  bath.  Dissolve 
the  dry  fatty  acids  by  warming  with  100  cc.  of  90%  alcohol  by  volume  and  cool 
slowly  to  15°C.,  shaking  to  aid  crystallization.  Allow  to  stand  at  15°C.  for  30 
minutes.  In  the  presence  of  peanut  oil,  crystals  of  arachidic  acid  will  separate  from 
the  solution.  Filter,  wash  the  precipitate  twice  with  10  cc.  of  90%  alcohol  by 
volume,  and  then  with  70%  alcohol  by  volume,  care  being  taken  to  maintain  the 
arachidic  acid  and  the  wash  solutions  at  a  definite  temperature  in  order  to  apply 
the  solubility  corrections  given  below.  Dissolve  the  arachidic  acid  upon  the  filter 
with  boiling  absolute  alcohol,  evaporate  to  dryness  in  a  weighed  dish,  dry  and 
weigh.  Add  to  the  weight  0.0025  gram  for  each  10  cc.  of  90%  alcohol  used  in  the 
crystallization  and  washing,  if  conducted  at  15°C.;  if  conducted  at  20°C.,  add  0.0045 
gram  for  each  10  cc.  The  melting  point  of  arachidic  acid  thus  obtained  is  71°- 
72°C.  Twenty  times  the  weight  of  arachidic  acid  will  give  the  approximate  amount 
of  peanut  oil  present.  Arachidic  acid  has  a  characteristic  appearance  and  may 
be  identified  by  the  microscope.  As  little  as  5-10%  of  peanut  oil  can  be  detected 
by  this  method. 

SESAME  OIL. 

38  Baudoin  Test. — Official. 

Dissolve  0.1  gram  of  finely  powdered  sugar  in  10  cc.  of  hydrochloric  acid  (sp. 
gr.  1.20),  add  20  cc.  of  the  oil  to  be  tested,  shake  thoroughly  for  a  minute  and  allow 
to  stand.  The  aqueous  solution  separates  almost  at  once  and,  in  the  presence  of 
even  a  very  small  admixture  of  sesame  oil,  is  colored  crimson.  Some  olive  oils 
give  a  slight  pink  coloration  with  this  reagent.  Comparative  tests  with  known 
samples  containing  sesame  oil  will  differentiate  them. 

39  Villavecchia  Test^^.— Official. 

Add  2  grams  of  furfural  to  100  cc.  of  95%  alcohol  by  volume  and  mix  thoroughly 
0.1  cc.  of  this  solution,  10  cc.  of  hydrochloric  acid  (sp.  gr.  1.20),  and  10  cc.  of  the  oil 
by  shaking  them  together  in  a  test  tube.  A  crimson  color  is  developed  as  in  the 
Baudoin  test,  38,  where  sugar  is  used. 

Villavecchia  explained  this  reaction  on  the  basis  that  furfural  is  formed  by  the 
action  of  levulose  and  hydrochloric  acid  and  therefore  substituted  furfural  for 
sucrose.  As  furfural  gives  a  violet  tint  with  hydrochloric  acid  it  is  necessary  to  use 
the  very  dilute  solution  specified  in  the  method. 

BEEF  FAT  IN  LARD. 

40  Emery  Method^°. —Tentative. 

Weigh  5  grams  of  the  melted  fat  into  a  glass-stoppered  25  cc.  cylinder  about 
150-175  mm.  in  height.  Add  warm  ether  up  to  the  25  cc.  mark,  stopper  securely 
and  shake  until  the  fat  is  completely  dissolved.  Allow  the  cylinder  to  stand  for 
about  18  hours  at  a  temperature  of  16°-20°C.  during  which  time  some  of  the  solid 
glycerides  will  crystallize  out.  Decant  the  clear  solution  carefully  from  the  crys- 
tals, wash  with  three  5  cc.  portions  of  cold  ether,  avoiding  breaking  up  the  deposit 
during  the  first  2  washings.  Agitate  the  crystals  with  the  third  portion  of  ether 
and  transfer  to  a  small  filter.  Wash  on  the  paper  with  successive  small  amounts 
of  cold  ether  until  15-20  cc.  have  been  used,  then  remove  the  last  traces  of  ether  by 
means  of  slight  suction  on  the  stem  of  the  funnel.  Break  up  any  large  lumps  and 
allow  the  deposit  to  dry. 


XXIII]  FATS   AND    OILS  315 

When  thoroughly  dry  pulverize  the  glycerides  and  take  their  melting  point  in  a 
closed  1  mm.  tube,  using  an  apparatus  similar  to  that  indicated  in  1 1 ,  Fig.  12.  Heat 
the  water  in  the  beaker  rapidly  to  about  55°C.  and  maintain  that  temperature 
until  the  thermometer  carrying  the  melting-point  tube  registers  50°-55°C.,  then 
heat  again  and  carry  the  temperature  of  the  outer  bath  somewhat  rapidly  to  G7°C. 
when  the  lamp  is  removed.  The  melting  point  of  the  crystals  is  regarded  as  that 
point  when  the  fused  substance  becomes  perfectly  clear  and  transparent.  A  dark 
background  placed  about  4  inches  from  the  apparatus  will  prove  of  advantage. 
When  the  melting  point  of  the  glycerides  obtained  by  this  method  is  below  63.4°C. 
the  presence  of  beef  fat  should  be  suspected,  while  a  melting  point  of  63°C.,  or  below, 
can  be  regarded  as  positive  evidence  that  the  sample  is  not  pure  lard.  It  is  advis- 
able to  carry  out  this  method  with  a  control  sample  of  pure  lard  in  connection  with 
each  batch  of  samples  analyzed. 

FISH  OIL  AND  MARINE  ANIMAL  OILS  IN  THE  PRESENCE  OF  VEGETABLE  OILS  AND  IN  THE 
ABSENCE  OF  METALLIC  SALTS. 

41  Qualilative  Tesl. — Tentative. 

Dissolve  in  a  test  tube  about  6  grams  of  the  oil  in  12  cc.  of  a  mixture  of  equal 
parts  of  chloroform  and  glacial  acetic  acid.  Add  bromin,  drop  by  drop,  until  a 
slight  excess  is  indicated  by  the  color,  keeping  the  solution  at  about  20°C.  Allow 
to  stand  15  minutes  or  more  and  then  place  the  test  tube  in  boiling  water.  If  vege- 
table oils  only  are  present,  the  solution  will  become  perfectly  clear,  while  fish  oils 
will  remain  cloudy  or  contain  a  precipitate  due  to  the  presence  of  insoluble  bromids. 

42  COLORING  MATTERS.-TENTATIVE. 
Proceed  as  directed  under  XI,  3. 

BIBLIOGRAPHY. 

^  Allen.     Commercial  Organic  Analysis.     4th  ed.,  1909-14,  2:50. 

2  Wiley.  Principles  and  Practice  of  Agricultural  Analysis.  2nd  ed.,  1906-14,  3: 
414;  Conn.  Agr.  Exp.  Sta.  Rept.,  1900,  (II),  p.  142. 

3  Ber.,  1882,  15:  1031;  J.  Am.  Chem.  Soc,  1899,  21:  991. 
«  J.  Soc.  Chem.  Ind.,  1898,  17:  1021. 

»  U.  S.  Bur.  Chem.  Bull.  13  (IV),  p.  448;  Lewkowitsch.  Chemical  Technology 
and  Analysis  of  Oils,  Fats  and  Waxes.  5th  ed.,  1913-15,  1 :  319;  Wiley.  Principles  and 
Practice  of  Agricultural  Analvsis.     2nd  ed.,  1906-14,  3 :  390. 

«  Arb.  kais.  Gesundh.,  1903-04,  20:  545. 

'  Lewkowitsch.  Chemical  Technology  and  Analvsis  of  Oils,  Fats  and  Waxes. 
5th  ed.,  1913-15,  2:425. 

8  Analyst,  1889,  14:  61;  J.  Am.  Chem.  Soc,  1893,  15:  110. 

9  J.  Soc. 'Chem.  Ind.,  1897,  16:503;  Benedikt.  Analyse  der  Fette  und  Wachs- 
arten.  5th  ed.,  1908,  p.  143;  Allen.  Commercial  Organic  Analysis.  4th  ed.,  1909-14, 
2:  33 

'  1"  U.  S.  Bur.  Animal  Industry  Circ.  212. 

"  Chem.  Ztg.,  1913,  37:  1001. 

"Allen.     Commercial  Organic  Analysis.     4th  ed.,  1909-14,  2:  79. 

"  Lewkowitsch.  Chemical  Technology  and  Analysis  of  Oils,  Fats  and  Waxes. 
5th  ed.,  1913-15,  1:343. 

i«  J.  pharm.  chim.,  1897,  6th  ser.,  6: 390;  Abs.  Analyst,  1897,  22: 326;  Allen.  Com- 
mercial Organic  Analysis.  4th  ed.,  1909-14,  2: 135;  Conn.  Agr.  Exp.  Sta.  Rept.,  1900 
(11),  p.  143. 

"Allen.     Commercial  Organic  Analj'sis.     4th  ed.,  1909-14,  2:  135. 

"  Abs.  J.  Soc.  Chem., Ind.,  1899,  18:  711. 

"  Compt.  rend.,  1871,  73:  1330;  Lewkowitsch.  Chemical  Technology  and  Analy- 
sis of  Oils,  Fats  and  Waxes.     5th  ed.,  1913-15,  2:  310. 

18  J.  Am.  Chem.  Soc,  1893,  15:  110. 

i«  J.  Soc.  Chem.  Ind.,  1893,  12:  67;  1894,  13:  69. 

"  U.  S.  Bur.  Animal  Industry  Circ.  132. 


XXIV.     SPICES  AND  OTHER  CONDIMENTS. 

SPICES. 

1  PREPARATION  OF  SAMPLE.— TENTATIVE. 

Grind  the  sample  so  as  to  pass  through  a  sieve  having  circular  openings  1  mm.  in 
diameter  and  mix  thoroughly.  Owing  to  the  lack  of  uniformity  of  most  spices 
and  the  peculiar  tendency  to  stratify,  extreme  care  is  necessary  in  weighing  out  a 
portion  for  analysis.  Stir  the  material  with  a  spoon,  having  a  capacity  of  approxi- 
mately 2  grams,  and  dip  a  spoonful  from  the  interior  in  order  that  only  a  very  small 
amount  needs  to  be  added  to  or  taken  from  the  portion  on  the  scale  pan.  In  the 
determination  of  starch  in  spices  by  the  diastase  method,  reduce  a  portion  of  the 
sample  to  an  impalpable  powder  by  grinding  in  a  mortar. 

2  MOISTURE.— TENTATIVE. 

Dry  2  grams  to  constant  weight  at  110°C.  From  the  resulting  loss  in  weight 
subtract  the  amount  of  volatile  ether  extract  as  determined  in  9. 

3  ASH.— OFFICIAL. 
Determine  as  directed  under  VIII,  4. 

4  SOLUBLE  AND  INSOLUBLE  ASH.— TENTATIVE. 
Proceed  as  directed  under  IX,  17,  employing  the  ash  obtained  in  3. 

5  ASH  INSOLUBLE  IN  ACID.— TENTATIVE. 

Boil  the  water-insoluble  residue,  obtained  in  4,  or  the  total  ash  obtained  in  3, 
with  25  cc.  of  10%  hydrochloric  acid  (sp.  gr.  1.050)  for  5  minutes,  collect  the  insol- 
uble matter  on  a  Gooch  or  an  ashless  filter,  wash  with  hot  water,  ignite  and  weigh. 

6  CALCIUM  OXID  IN  ASH.— OFFICLAL. 

Ignite  2-A  grams  of  the  sample  as  directed  under  3,  digest  with  hot  10%  hydro- 
chloric acid,  evaporate  to  dryness,  moisten  the  dry  residue  with  dilute  hydro- 
chloric acid  and  again  evaporate  to  drjmess  to  render  the  silica  insoluble.  Moisten 
the  residue  with  5-10  cc.  of  hydrochloric  acid,  add  about  50  cc.  of  water,  allow  to 
stand  on  a  water  bath  for  a  few  minutes,  filter  and  wash  the  insoluble  residue  with 
hot  water.  Determine  calcium  oxid  in  the  combined  filtrate  and  washings  as  directed 
under  XXVIII,  23. 

7  NITROGEN.— OFFICIAL. 

Determine  as  directed  under  I,  18,  21  or  23,  except  in  the  case  of  black  and 
white  peppers  in  which  use  only  the  Kjeldahl-Gunning-Arnold  method'  [I,  23], 
employing  1  gram  of  the  sample. 

NITROGEN  IN  NON-VOLATILE  ETHER  EXTRACT. 

8  Wititon,  Ogden  and  Mitchell  Method. — Tentative. 

(For  black  and  white  peppers.) 

Extract  10  grams  of  the  pepper  for  20  hours  in  a  continuous  extraction  apparatus 
with  absolute  ether,  collecting  the  extract  in  a  weighed  250  cc.  flask.    Evaporate 

317 


318  METHODS    OF   ANALYSIS  [Chap. 

the  ether,  dry  first  at  100°C.  and  finally  to  constant  weight  at  110°C.  Determine 
the  nitrogen  in  the  weighed  extract,  as  directed  in  I,  23,  digesting  in  the  same  flask 
used  for  the  extraction.  Calculate  the  parts  of  nitrogen  per  100  parts  of  non-vola- 
tile ether  extract.  If  desired,  crude  piperin  may  be  calculated  from  the  nitrogen 
by  multiplying  by  20. 3G. 

9  VOLATILE  AND  NON-VOLATILE  ETHER  EXTRACT^.— TENTATIVE. 

Extract  2  grams  of  the  ground  material  for  20  hours  in  a  continuous  extrac- 
tion apparatus  with  anhydrous  ether  [VIII,  9].  Transfer  the  ethereal  solution  to 
a  tared  capsule  and  allow  to  evaporate  at  room  temperature.  Let  stand  for  18 
hours  over  sulphuric  acid  and  weigh  the  total  ether  extract.  Heat  the  extract 
gradually  and  then  to  constant  weight  at  110°C.  The  loss  is  volatile  ether  extract; 
the  residue,  non-volatile  ether  extract. 

10  ALCOHOL  EXTRACT^.-TENTATIVE. 

Place  2  grams  of  the  sample  in  a  100  cc.  flask  and  fill  to  the  mark  with  95%  alcohol 
by  volume.  Stopper,  shake  for  8  hours  at  30  minute  intervals  and  allow  to 
stand  for  16  hours  longer  without  shaking.  Filter  the  extract  through  a  dry 
filter,  evaporate  a  50  cc.  aliquot  of  the  filtrate  to  dryness  in  a  flat-bottomed  dish 
on  a  water  bath  and  heat  to  constant  weight  at  110°C. 

11  COLD-WATER  EXTRACT.-TENTATIVE. 

(For  ginger.) 

Place  4  grams  of  the  sample  in  a  200  cc.  graduated  flask,  add  water  to  the  mark, 
shake  at  30  minute  intervals  during  8  hours  and  let  stand  16  hours  longer  with- 
out shaking.  Filter  and  evaporate  a  50  cc.  aliquot  of  the  filtrate  to  dryness  in  a 
flat-bottomed,  metal  dish.     Dry  to  constant  weight  at  100°C. 

1  2  COPPER-REDUCING  SUBSTANCES  BY  DIRECT  INVERSION.— TENTATIVE. 

Extract  4  grams  of  the  sample  with  5  successive  portions  of  10  cc.  of  ether  on  a 
filter  that  will  retain  completely  the  smallest  starch  granules.  After  the  ether 
has  evaporated,  wash  with  150  cc.  of  10%  alcohol  by  volume. 

Owing  to  the  formation  of  a  glutinous  mass  which  clogs  the  filter,  it  is  not  possible 
to  wash  samples  of  Batavia  cassia  with  water  or  dilute  alcohol.  Therefore  all  pre- 
liminary washing  is  best  omitted  in  determinations  made  on  all  varieties  of  cassia, 
as  well  as  on  cassia  buds  and  cinnamon. 

Carefully  wash  the  residue  from  the  paper  into  a  .500  cc.  flask  with  200  cc.  of 
water,  using  a  small  wash  bottle,  and  gently  rubbing  the  paper  with  the  tip  of  the 
finger.  Hydrolyze  and  determine  the  copper  reducing  material  as  directed  under 
VIII,  60.     Express  the  result  in  terms  of  starch. 

13  STARCH.— TENTATIVE. 

Extract  4  grams  of  the  finely  pulverized  sample  with  ether  and  10%  alcohol  by 
volume,  as  directed  under  12,  and  determine  starch  by  the  diastase  method,  as 
directed  under  VIII,  62. 

14  CRUDE  FIBER.— TENTATIVE. 

Proceed  as  directed  under  VIII,  68,  and  remove  all  ether  extractives  by  suc- 
cessive washings  of  the  dry  fiber  with  ether  previous  to  weighing. 


XXrV]  SPICES   AND    OTHER   CONDIMENTS  319 

15  TANNIN.— TENTATIVE. 

(For  cloves  and  allspice.) 

Extract  2  grams  of  the  sample  for  20  hours  with  anhydrous  ether.  Boil  the 
residue  for  2  hours  with  300  cc.  of  water,  cool,  make  up  to  .500  cc.  and  filter.  Measure 
25  cc.  of  this  infusion  into  a  1200  cc.  flask,  add  20  cc.  of  indigo  solution,  7o0  cc.  of 
water  and  proceed  as  directed  under  XVI,  32.  One  cc.  of  N/10  oxalic  acid  is 
equivalent  to  0.006232  gram  of  quercitannic  acid,  or  0.0008  gram  of  oxygen  absorbed. 

16  TOTAL  SULPHUR.-OFFICIAL. 

(For  mustard.) 
Proceed  as  directed  under  III,  17. 

OLIVE  OIL, 

(For  paprika.) 

17  Qualitative  Test. — Tentative. 

Spread  5  grams  of  the  paprika  on  a  watch  glass  and  dry  over  sulphuric  acid  for 
at  least  12  hours.  Measure  250  cc.  of  anhydrous,  alcohol-free  ether  [VIII,  9]  into  a 
graduated  flask  on  which  the  mark  is  situated  near  the  lower  end  of  the  neck,  and 
brush  the  paprika  into  it.  Place  a  mark  on  the  neck  of  the  flask  at  the  point  where 
the  meniscus  is,  and  allow  to  stand  for  an  hour,  shaking  at  20  minute  intervals 
during  that  time.  Bring  the  meniscus  back  to  the  mark  placed  upon  the  neck,  either 
by  cooling  the  flask  and  contents  if  the  level  has  risen,  or  by  adding  absolute  ether 
if  it  has  fallen;  let  the  solid  particles  settle  and  pipette  off  100  cc.  of  the  supernatant 
liquid,  filter  through  an  11  cm.  closely  woven  paper  into  a  tared,  air-dry,  250  cc, 
glass-stoppered  Erlenmeyer  flask  that  has  been  counterpoised  against  a  similar 
flask;  wash  the  paper  with  a  little  absolute  ether.  Then  distil  off  the  solvent  and 
remove  the  flask  from  the  bath  as  soon  as  the  ether  ceases  to  come  over.  Lay  the 
flask  on  its  side  in  a  water  oven  and  heat  for  30  minutes;  cool  the  open  flask  for  at 
least  30  minutes  in  the  air  and  weigh.  Repeat  this  heating  and  weighing  until  the 
weight  is  constant  to  within  1  mg.,  2  heatings  usually  being  sufficient.  Note  the 
per  cent  of  ether  extract  obtained.  If  more  than  U  hours  of  heating  are  required 
to  obtain  constant  weight,  or  if  the  ether  extract  becomes  colorless,  reject  it  and 
start  a  new  determination  with  freshly  purified  ether. 

Dissolve  the  ether  extract  in  the  flask  with  10  cc.  of  chloroform,  add  30  cc.  of 
Hanus'  solution  [XXIII,  17  (a)]  and  proceed  as  directed  under  XXIII,  18,  allow- 
ing 30  minutes  for  the  halogen  absorption.  Note  the  iodin  number  of  the  ether 
extract.  The  iodin  number  of  pure  paprika  thus  obtained  should  not  be  less  than 
125. 

MICROSCOPIC  EXAMINATION.-TENTATIVE. 

18  GENERAL. 

Adulterants  of  vegetable  origin  in  spices  are  detected  best  by  means  of  the  mi- 
croscope. A  general  knowledge  of  vegetable  histologj'  and  the  microscopic  appear- 
ance of  the  spices  and  spice  adulterants  is  essential.  Some  of  the  standard  works* 
on  these  subjects  are  listed  in  the  bibUography. 

19  REAGENTS. 

Of  the  numerous  reage'nts  employed  in  histological  work  the  following  are  the 
most  u.«!eful  in  spice  examinations : — 

(a)  Glycerol  solution  {1  to  1). 

(b)  Absolute  alcohol. 


320  METHODS    OF   ANALYSIS  [Chap. 

(C)  Ether. 

(d)  Ammonium  hydroxid. — The  concentrated  solution,  containing  about  30%  of 
ammonia  gas,  is  used  in  making  Schweitzer's  reagent  and  for  some  other  purposes. 
For  the  turmeric  test  the  concentrated  solution  should  be  diluted  with  10  parts  of 
water. 

(e)  5%  potassium  hydroxid  solution. 

(f)  Chloral  hydrate  solution  (8  to  5). 

(g)  Schultze's  mixture. — Crystallized  potassium  chlorate  mixed  with  nitric  acid 
as  needed. 

(h)  lodin-potassium  iodid  solution. — A  solution  of  0.05  gram  of  iodin,  0.2  gram 
of  potassium  iodid  in  15  cc.  of  water. 

(i)  Chlor-zinc  iodin  solution. — Dissolve  100  grams  of  zinc  chlorid  in  60  cc.  of  water 
and  to  this  add  20  grams  of  potassium  iodid  and  0.5  gram  of  iodin  crystals.  A  few 
crystals  of  iodin  should  be  left  in  the  bottle  to  insure  saturation  and  allowed  to 
stand  a  few  hours  before  using.  The  chlor-zinc  iodin  solution,  pi-epared  in  this 
manner,  will  keep  for  months.  If  the  color  developed  in  the  tissue  is  too  deep  a  blue, 
a  very  slight  dilution  of  the  reagent  is  advisable. 

(j)  Millon's  reagent. — Prepare  as  in  XV,  9. 

(k)  1%  ferric  acetate  or  chlorid  solution. — Freshly  prepared. 

(1)  Alkanna  tincture. — Macerate  20  grams  of  alkanet  root  for  several  days  with 
100  cc.  of  alcohol. 

(m)  Aqueous  safranin  solutioyi. 

(n)  10%  hydrochloric  acid. 

(O)  Acetic  aad.— Glacial  or  99%  acetic  acid  diluted  with  2  parts  of  water. 

20  APPARATUS. 

(a)  Dissecting  microscope  or  hand  lens. 

(b)  Compound  microscope. — Provided  with  |  and  I  inch  objectives,  1  and  2  inch 
oculars,  double  nosepiecc,  eyepiece  micrometer  and  polarizing  apparatus. 

(C)  Sieves. — A  series  of  sieves  with  meshes  ranging  from  0.2-2  mm. 
(d)  Slides,  cover-glasses,  needles,  scalpels,  forceps,  etc. 

21  PREPARATION   OF   SAMPLE. 

Reduce  one  portion  to  a  fine  powder  in  a  mortar.  Separate  another  portion  into 
several  grades  of  fineness  by  sieves  of  different  mesh  or  by  jarring  on  a  sheet  of 
paper.  In  the  coarser  grades,  fragments  of  a  suspicious  nature  may  often  be  seen 
with  the  naked  eye  or  under  a  simple  microscope;  these  should  be  picked  out  for 
subsequent  examination  under  the  compound  microscope. 

22  EXAMINATION. 

Mount  a  small  quantity  of  the  ground  sample  in  water  and  examine  under  the 
compound  microscope  with  both  ordinary  and  polarized  light.  This  gives  general 
information  as  to  the  nature  of  the  material  and  serves  for  the  detection  and  iden- 
tification of  starch  granules  and  various  tissues.  Draw  a  small  drop  of  the  iodin- 
potassium  iodid  solution  into  the  same  preparation  by  means  of  a  piece  of  filter 
paper  placed  on  the  opposite  edge  of  the  cover-glass  and  examine.  Starch  gran- 
ules will  be  colored  blue  or  blue-black,  cellulose  j^ellow,  and  proteins  either  brown 
or  yellow. 

In  the  manner  just  described  draw  a  little  of  the  5%  potassium  hydroxid  solution 
under  the  cover-glass  and  again  examine.     This  treatment  gelatinizes  the  starch 


XXIV]  SPICES   AND    OTHER   CONDIMENTS  321 

granules,  dissolves  the  proteins,  saponifies  the  fats,  and  in  other  ways  clears  the 
preparation.  It  also  imparts  to  tannins  a  reddish  color.  If  this  treatment  does 
not  clear  the  tissues  satisfactorily,  treat  a  fresh  portion  for  some  hours  with  the 
chloral  hydrate  solution. 

Examine  also  the  crude  fiber  obtained  in  the  chemical  analysis,  as  in  this  mate- 
rial the  stone  cells  and  other  tissues  are  shown  distinctly. 

To  isolate  stone  cells,  bast  fibers  and  other  thick-walled  cells  macerate  a  por- 
tion of  the  sample  in  Schultze's  mixture,  using  such  proportion  of  potassium  chlor- 
ate and  nitric  acid  and  heating  for  such  a  time  as  secures  the  desired  results.  Pow- 
dered charcoal  and  charred  shells  resist  the  bleaching  action  of  potash,  chloral 
hydrate  and  Schultze's  mixture. 

If  it  is  desired  to  distinguish  cellulose  from  infiltrated  substances  (lignin,  suberin, 
etc.),  add  the  freshly  prepared  chlor-zinc  iodin  solution  to  a  water  mount,  whereby 
the  former  is  colored  blue  and  the  latter  yellow. 

Test  for  proteins  by  cautiously  warming  on  a  slide  with  a  drop  of  freshly  pre- 
pared Millon's  reagent.  The  proteins  are  partially  decomposed,  acquiring  grad- 
ually a  brick-red  color.  If  it  is  desired  to  study  the  form  of  the  aleurone  (pro- 
tein) granules,  which  in  some  plants  are  quite  as  characteristic  as  starch  granules, 
prepare  a  mount  in  pure  glycerol  or  oil. 

To  distinguish  fats,  oils,  essential  oils  and  resins  from  other  cell  contents,  treat 
for  an  hour  with  the  alkanna  tincture,  diluted  with  an  equal  bulk  of  water,  which 
imparts  to  these  substances  a  deep  red  color,  or  treat  with  ether,  which  dissolves 
them.  Treat  also  with  alcohol,  which  dissolves  the  essential  oils  and  resins,  but 
does  not  perceptibly  affect  the  fats  and  oils. 

In  testing  for  tannins  and  tissues  impregnated  with  these  substances,  add  the 
1%  ferric  acetate  or  chlorid  solution.  Both  of  these  reagents  give  a  green  or  blue 
color  with  tannins,  but  the  former  acts  more  slowly  and  is  to  be  preferred. 

Crystals  of  calcium  oxalate  are  recognized  by  their  characteristic  forms  and 
their  behavior  to  polarized  light.  To  distinguish  calcium  oxalate  from  calcium 
carbonate,  treat  with  acetic  acid,  which  does  not  affect  the  former,  but  dissolves 
the  latter  with  effervescence.     Both  arc  soluble  in  hydrochloric  acid. 

PREPARED  MUSTARD. 

23  PREPARATION  OF  SAMPLE.-TENTATIVE. 

Transfer  the  entire  contents  of  the  container  to  a  dish  sufficiently  large  to  stir 
thoroughly  and  make  the  whole  mass  homogeneous.  Preserve  in  a  bottle  having 
a  tightly  fitting  glass  stopper.  Stir  well  each  time  before  removing  a  portion  for 
analysis. 

24  SOLIDS.-TENTATIVE. 

Weigh  5  grams  of  the  sample  into  a  flat-bottomed,  platinum  dish,  distribute 
evenly  over  the  bottom  of  the  dish  with  a  little  water,  place  on  a  water  bath  until 
the  mixture  appears  dry,  and  heat  finally  to  constant  weight  at  100°C.  in  a  water 
oven. 

25  ASH.-OFFICIAL. 

Ignite  the  dry  residue,  obtained  in  the  determination  of  solids,  24,  as  directed 
under  VIII,  4. 

26  SALT.-TENTATIVE. 

Determine  chlorin  in  the  ash  as  directed  under  III,  15. 


322  METHODS    OF   ANALYSIS  [Chap. 

27  ETHER  EXTRACT.— TENTATIVE. 

Weigh  10  grams  of  the  sample  into  a  capsule  and  mix  with  about  30  grams  of 
sand.  Heat  on  a  water  bath  until  the  mixture  appears  dry  and  complete  the  dry- 
ing in  a  water  oven.  Grind  until  all  the  lumps  are  broken  up,  and  determine  the 
ether  extract  as  directed  under  VIII,  10. 

28  PROTEIN.— OFFICIAL. 

Determine  the  nitrogen  as  directed  under  I,  18,  21  or  23,  using  5  grams  of  the 
sample.    Multiply  the  result  by  6.25  to  obtain  the  amount  of  protein. 

29  ACIDITY.-TENTATIVE. 

Weigh  10  grams  of  the  sample  into  a  200  cc.  graduated  flask,  make  up  to  the 
mark  with  water,  shake,  filter  through  a  dry  paper  and  determine  the  acidity  in 
100  cc.  by  titration  with  N/10  alkali,  using  phenolphthalein  as  an  indicator.  Ex- 
press the  result  as  acetic  acid.  One  cc.  of  N/10  alkali  is  equivalent  to  0.0060  gram 
of  acetic  acid. 

30  COPPER-REDUCING  SUBSTANCES.-TENTATIVE. 

By  Direct  Inversion. 

Proceed  as  directed  under  VIII,  60,  except  that  10  grams  of  the  sample,  without 
previous  washing  or  extraction,  are  treated  directly  with  200  cc.  of  water  and  20  cc. 
of  25%  hydrochloric  acid  and  the  solution  is  made  up  to  250  cc.  after  neutralizing 
and  before  filtering  and  drawing  off  the  aliquot.  In  analyses  of  samples  contain- 
ing starch,  particular  attention  should  be  given  that  the  amount  of  dextrose 
present  in  the  aliquot  taken  for  the  reducing  sugar  determination  docs  not  exceed 
the  maximum  permitted  for  that  determination.  Calculate  the  result  in  terms  of 
starch. 

31  CRUDE  FIBER.— TENTATIVE. 

Transfer  8  grams  of  the  sample  (equivalent  to  about  2  grams  of  dry  matter)  to  a 
porcelain  or  glass  mortar.  Treat  with  a  little  hot  1.25%  sulphuric  acid  and  rub  into 
a  uniform  thin  paste.  It  is  absolutely  essential  that  this  paste  be  uniform  in  con- 
sistency and  entirely  free  from  lumps.  Rinse  the  thin  mixture  into  a  500  cc.  Erlen- 
meyer  flask,  using  a  total  volume  of  200  cc.  of  the  hot  1.25%  sulphuric  acid  for  the 
entire  operation.  Proceed  as  directed  under  VIII,  68,  and  remove  all  the  fat,  pre- 
vious to  weighing  of  the  crude  fiber,  by  repeated  washings  of  the  dry  fiber  with 
ether. 

32  COLORING  MATTERS.— TENTATIVE. 
Proceed  as  directed  under  XI. 

33  PRESERVATIVES.-TENTATIVE. 
Proceed  as  directed  under  X. 

TOMATO  PRODUCTS. 

34  PREPARATION  OF  SAMPLE.-TENTATIVE. 

Shake  the  package  and  contents  thoroughly  to  incorporate  any  sediment,  then 
transfer  the  entire  contents  of  the  container  to  a  large  glass  or  porcelain  dish  and 
mix  thoroughly,  continuing  the  stirring  for  at  least  1  minute.  Transfer  the  well 
mixed  sample  to  a  glass-stoppered  container  and  shake  or  stir  thoroughly  each  time 
before  removing  portions  for  analysis. 


XIV]  SPICES   AND    OTHER    CONDIMENTS  323 

5  TOTAL  SOLIDS— TENTATIVE. 

Weigh  10  grams  of  the  sample  into  a  flat-bottomed,  platinum  dish  having  a  diam- 
eter of  about  6  cm.,  spread  the  sample  in  a  thin  layer,  evaporate  to  dryness  on  a 
steam  bath  and  dry  in  a  water  oven  for  4  hours. 

36  INSOLUBLE  SOLIDS.-TENTATIVE. 

Wash  20  grams  of  the  sample  repeatedly  with  hot  water,  ccntrifugalizing  after 
each  addition  of  water  and  pouring  the  clear,  supernatant  liquid  through  a  tared- 
triple  filter  paper  on  a  Biichner  funnel.  After  4-5  washings  transfer  the  remaining 
insoluble  matter  to  the  filter,  dry  for  2  hours  at  100°C.,  cool  in  a  desiccator  and 
weigh  rapidly.  The  paper  used  should  be  dried  for  2  hours  at  100°C.,  cooled  in  a 
desiccator  and  weighed.  A  cylinder,  1-1  f  inches  in  diameter  and  5-6  inches  long, 
is  convenient  for  washing  and  centrifugalizing. 

37  SOLUBLE  SOLIDS.-TENTATIVE. 

Subtract  the  percentage  of  insoluble  solids  from  the  percentage  of  total  solids 
to  obtain  the  percentage  of  soluble  solids. 

38  SAND.-TENTATIVE. 

Weigh  100  grams  of  the  well  mixed  sample  into  a  2-3  liter  beaker,  nearly  fill  the 
beaker  with  water,  and  mix  the  contents  thoroughly.  Allow  to  stand  5  minutes 
and  decant  the  supernatant  liquid  into  a  second  beaker.  Refill  the  first  with  water 
and  again  mix  the  contents.  After  5  minutes  more  decant  the  second  beaker  into 
a  third,  the  first  into  the  second,  refill  and  again  mix  the  first.  Continue  this  opera- 
tion, decanting  from  the  third  beaker  into  the  sink  until  the  lighter  material  is 
washed  out  from  the  ketchup.  Then  collect  the  sand  from  the  3  beakers  on  a  tared 
Gooch  crucible,  dry,  ignite  and  weigh.  Attention  is  especially  called  to  the  fact 
that  under  "Sand"  only  the  figure  obtained  by  this  method  should  be  reported. 
The  results  obtained  by  the  determination  of  ash  insoluble  in  hydrochloric  acid 
are  not  applicable  to  the  determination  of  sand,  since  the  sand  is  so  unevenly  dis- 
tributed that  reliable  results  can  only  be  obtained  by  taking  a  larger  sample  than 
is  possible  in  the  determination  of  ash. 

39  ASH.-OFFICIAL. 

Evaporate  10  grams  of  the  sample  to  dryness  on  a  water  bath  and  ignite  as  directed 
under  VIII,  4. 

40  ALKALINITY  OF  THE  ASH.— TENTATIVE. 

Proceed  as  directed  under  XIII,  7.  Express  the  result  as  the  number  of  cc.  of 
N/10  acid  required  to  neutralize  the  ash  from  100  grams  of  the  sample. 

41  SODIUM  CHLORID.— OFFICIAL. 

Proceed  as  directed  under  III,  15,  using  either  an  aliquot  of  the  solution  obtained 
in  40  or  a  nitric  acid  solution  of  the  whole  ash. 

42  REDUCING  SUGARS  BEFORE  INVERSION.-TENTATIVE. 

Weigh  20  grams  of  the  sample  into  a  200  cc.  flask,  dilute  with  about  100  cc.  of 
water,  clarify  with  a  slight  excess  of  neutral  lead  acetate  solution,  dilute  to  the 
mark  and  filter.  Remove  the  excess  of  lead  with  anhydrous  sodium  or  potassium 
oxalate.  Filter  and  determine  reducing  sugars  as  directed  under  Vlll,  25.  Ex- 
press the  result  as  per  cent  of  invert  sugar. 


324.  METHODS    OF   ANALYSIS  [Chap. 

43  REDUCING  SUGARS  AFTER  INVERSION. -TENTATIVE. 

Transfer  50  cc.  of  the  filtrate,  obtained  in  42,  to  a  100  cc.  flask,  add  5  cc.  of  con- 
centrated hydrochloric  acid  and  let  stand  overnight.  Nearly  neutralize  with 
sodium  hydroxid  solution,  cool,  dilute  to  the  mark  and  determine  reducing  sugars 
in  an  aliquot  as  directed  under  VIII,  25.  Express  the  result  as  per  cent  of  invert 
sugar. 

44  SUCROSE.— TENTATIVE. 
Proceed  as  directed  under  VIII,  1 8. 

45  TOTAL  ACIDS.-TENTATIVE. 

Proceed  as  directed  under  XIX,  17,  employing  5  grams  of  the  sample.  Express 
the  result  as  anhydrous  citric  acid.  One  cc.  of  N/'IO  alkali  is  equivalent  to  0.0064 
gram  of  anhydrous  citric  acid. 

46  VOLATILE  ACIDS.-TENTATIVE. 

Proceed  as  directed  under  XVI,  27,  employing  25  grams  of  the  sample,  increas- 
ing the  amount  of  water  used  for  the  distillation  and  collecting  a  correspondingly 
larger  amount  of  distillate.  Express  the  result  as  acetic  acid.  One  cc.  of  N/10 
alkali  is  equivalent  to  0.0060  gram  of  acetic  acid.  Reserve  the  neutralized  distillate 
for  the  detection  of  butyric  acid. 

BUTYRIC  ACID. 

47  Qualitative  Test. — Tentative. 

,    Evaporate  the  neutralized  distillate,  obtained  in  46,  to  dryness  on  a  steam  bath. 
Decompose  the  residue  with  about  5  cc.  of  10%  sulphuric  acid  and  note  the  odor. 

48  FIXED  ACIDS.-TENTATIVE. 

Multiply  the  percentage  of  volatile  acids,  48,  by  1.067  and  subtract  the  product 
from  the  percentage  of  total  acids,  45,  to  obtain  the  per  cent  of  fixed  acids  as  citric 
acid. 

Micro-Analysis  of  Tomato  Pulp,  Ketchup,  Puree  and  Sauce  (Paste). 

49  apparatus. 

(a)  Compound  microscope. — Giving  magnifications  of  approximately  90,  180  and 
500  diameters.  These  diameters  can  be  obtained  by  a  microscope  equipped  with 
16  and  8  mm.  apochromatic  objectives  and  a  X6  and  a  X18  compensating  ocular 
(a  X12  ocular  may  also  be  used  if  desired). 

(b)  Thoma-Zeiss  blood  counting  cell. 

(C)  Special  Thoma-Zeiss  cell. — With  the  central  disk  of  19  mm.  diameter  for 
making  the  mold  count^. 

50  molds.-tentative. 

Clean  the  special  Thoma-Zeiss  cell  so  that  Newton's  rings  are  produced  be- 
tween the  slide  and  the  cover-glass.  Remove  the  cover  and  place,  by  means  of  a 
knife  blade  or  scalpel,  a  small  drop  of  the  sample  upon  the  central  disk;  spread  the 
drop  evenly  over  the  disk  and  cover  with  the  cover-glass  so  as  to  give  an  even  spread 
to  the  material. 


XXIV]  SPICES   AND    OTHER    CONDIMENTS  325 

It  is  of  the  utmost  importance  that  the  drop  be  mixed  thoroughly  and  spread 
evenly,  otherwise  the  insohil)le  matter,  and  consequently  the  molds,  are  most  abun- 
dant at  the  center  of  the  drop.  Squeezing  out  of  the  more  liquid  portions  around 
the  margin  must  be  avoided.  In  a  satisfactory  mount  Newton's  rings  should  be 
apparent  when  finally  mounted  and  none  of  the  liquid  should  be  drawn  acro.s3  the 
moat  and  under  the  cover-glass. 

Place  the  slide  under  the  microscope  and  examine  with  about  90  diameters  and 
with  such  adjustment  that  each  field  of  view  represents  approximately  1.5  sq.  mm. 
of  area  on  the  mount. 

Observe  each  field  as  to  the  presence  or  absence  of  mold  filaments  and  note  the 
result  as  positive  or  negative.  Examine  at  least  50  fields,  prepared  from  2  or  more 
mounts.  No  field  should  be  considered  positive  unless  the  aggregate  length  of  the 
filaments  present  exceeds  approximately  one  sixth  the  diameter  of  the  field.  Cal- 
culate the  proportion  of  positive  fields  from  the  results  of  the  examination  of  all 
the  observed  fields  and  report  as  percentage  of  fields  containing  mold  filaments. 

51  YEASTS  AND  SPORES.— TENTATIVE. 

Fill  a  graduated  cylinder  with  water  to  the  20  cc.  mark,  and  then  add  the  sample 
till  the  level  of  the  mixture  reaches  the  30  cc.  mark.  Close  the  graduate,  or  pour 
the  contents  into  an  Erlenmeyer  flask,  and  shake  the  mixture  vigorously  15-20  sec- 
onds. To  facilitate  thorough  mixing  the  mixture  should  not  fill  more  than  three 
fourths  of  the  container  in  which  the  shaking  is  performed.  For  tomato  sauce  or 
pastes,  or  products  running  very  high  in  the  number  of  organisms,  or  of  heavy  con- 
sistency, 80  cc.  of  water  should  be  used  with  10  cc.  or  10  grams  of  the  sample. 
In  the  case  of  exceptionally  thick  or  dry  pastes,  it  may  be  necessary  to  make  an 
even  greater  dilution. 

Pour  the  mixture  into  a  beaker.  Thoroughly  clean  the  Thoma-Zeiss  counting 
cell  so  as  to  give  good  Newton's  rings.  Stir  thoroughly  the  contents  of  the  beaker 
with  a  scalpel  or  knife  blade,  and  then,  after  allowing  to  stand  3-5  seconds,  remove 
a  small  drop  and  place  upon  the  central  disk  of  the  Thoma-Zeiss  counting  cell  and 
cover  immediately  with  the  cover-glass,  observing  the  same  precautions  in  mount- 
ing the  sample  as  given  under  50.  Allow  the  slide  to  stand  not  less  than  10  min- 
utes before  beginning  to  make  the  count.  Make  the  count  with  a  magnification 
of  about  180  (8  mm.  apochromatic  objective  with  the  X6  compensating  ocular). 

Count  the  number  of  yeasts  and  spores  on  one  half  of  the  ruled  squares  on  the 
disk  (this  amounts  to  counting  the  number  in  S  of  the  blocks,  each  of  which  con- 
tains 25  of  the  small  ruled  squares) .  The  total  number  thus  obtained  equals  the  num- 
ber of  organisms  in  l/60cmm.  if  a  dilution  of  1  part  of  the  sample  with  2  parts  of  water 
is  used.  If  a  dilution  of  1  part  of  the  sample  with  8  parts  of  water  is  used, 
the  number  must  be  multiplied  by  3.  In  making  the  counts,  the  analyst  should 
avoid  counting  an  organism  twice  when  it  rests  on  a  boundary  line  between  2  adja- 
cent squares. 

52  BACTERIA.-TENTATIVE. 

Estimate  the  bacteria  from  the  mounted  sample,  used  in  51,  but  allow  the  sample 
to  stand  not  less  than  15  minutes  after  mounting  before  counting.  Use  a  magnifi- 
cation of  about  500  (8  mm.  apochromatic  objective  and  X18  compensating  ocular). 
Because  of  the  somewhat  clearer  definition  obtained  with  the  X12  compensating 
ocular,  some  prefer  it  to  the  X18,  though  the  magnification  is  correspondingly  less, 
being  about  375.  Count  and  record  the  number  of  bacteria  in  a  small  area  consist- 
ing of  5  of  the  small  sized  squares.     Move  the  slide  to  another  portion  of  the  field 


326  METHODS   OF  ANALYSIS 

and  count  the  number  on  another  similar  area.  Count  5  such  areas,  preferably  1 
from  near  each  corner  of  the  ruled  portion  of  the  slide  and  1  from  near  the  center. 
Determine  the  average  number  of  bacteria  per  area  and  multiply  by  2,400,000  which 
gives  the  number  of  bacteria  per  cc.  If  a  dilution  of  1  part  of  the  sample  with 
8  parts  of  water  instead  of  1  part  of  the  sample  with  2  parts  of  water  is  used  in 
making  up  the  sample,  then  the  total  count  obtained  as  above  must  be  multiplied 
by  7,200,000.     Omit  the  micrococci  type  of  bacteria  in  making  the  count. 

BIBLIOGRAPHY. 

1  Z.  anal.  Chem.,  1892,  31:  525;  Conn.  Agr.  Exp.  Sta.  Kept.,  1898,  (II),  p.  190. 

2  U.  S.  Bur.  Chem.  Bull.  13  (II),  p.  165. 

3  Conn.  Agr.  Exp.  Sta.  Kept.,  1898,  (II),  p.  187. 

*  Winton.  Microscopy  of  Vegetable  Foods.  2nd  ed.,  1916;  Vogl.  Die  wichtig- 
sten  vegetabilischen  Nahrungs-und  Genussmittel.  1899;  Tschirch  und  Oesterle. 
Anatomischer  Atlas  der  Pharmakognosie  und  Nahrungsmittelkunde.  1900;  Greenish 
and  Collin.  Anatomical  Atlas  of  Vegetable  Powders.  1904;  Greenish.  Microscopical 
Examination  of  Foods  and  Drugs.  2nd  ed.,  1910;  Koch.  Die  Mikroscopische  Ana- 
lyse der  Drogenpulver.  1900-08. 

'  U.  S.  Bur.  Chem.  Circ.  68,  p.  4. 


XXV.    CACAO  PRODUCTS. 


PREPARATION  OF  SAMPLE.-TENTATIVE. 


Mix  powdered  products  thoroughly  and  preserve  in  tightly  stoppered  bottles. 
Chill  sweet  or  bitter  chocolate  until  it  becomes  hard  and  reduce  to  a  finely  granu- 
lar condition  by  grating  or  shaving.  Mix  thoroughly  and  preserve  in  a  tightly 
stoppered  bottle  in  a  cool  place. 

2  MOISTURE.-OFFICIAL. 

Proceed  as  directed  under  IX,  2. 

3  ASH.-OFFICIAL. 

Proceed  as  directed  under  VIII,  4,  employing  sufficient  sample  to  contain  approxi- 
mately 1  gram  of  water-,  sugar-  and  fat-free  material. 

4  ASH  INSOLUBLE  IN  ACID.-TENTATIVE. 
Proceed  as  directed  under  XXTV,  5. 

5  SOLUBLE  AND  INSOLUBLE  ASH.-TENTATIVE. 

Proceed  as  directed  under  EX,  17,  employing  sufficient  sample  to  contain  ap- 
proximately 1  gram  of  water-,  sugar-  and  fat-free  material. 

6  ALKALINITY  OF  THE  SOLUBLE  ASH.— TENTATIVE. 
Proceed  as  directed  under  IX,  18. 

7  ALKALINITY  OF  THE  INSOLUBLE  ASH.-TENTATIVE. 

Proceed  as  directed  under  IX,  19. 

8  TOTAL  NITROGEN.-OFFICIAL. 

Determine  total  nitrogen  as  directed  under  I,  18,  21  or  23. 

9  CRUDE  FIBER.— TENTATIVE. 

Proceed  as  directed  under  VIII,  68,  employing  sufficient  sample  to  contain  ap- 
proximately 1  gram  of  water-,  sugar-  and  fat-free  material,  except  that  both  filtra- 
tions  should  be  made  upon  paper,  the  washed  fiber  either  being  weighed  upon  a 
tared  filter  in  the  usual  way  or  rinsed  from  the  paper  into  a  tared  Gooch,  dried  and 
weighed. 

The  residue  after  fat  extraction  may  be  used  directly  for  the  crude  fiber  deter- 
mination in  the  analysis  of  commercial  cocoa  and  other  finely  ground  or  pulver- 
ized cacao  products.  If,  however,  the  material  is  at  all  granular,  it  should  be  re- 
duced to  an  impalpable  powder;  otherwise  the  results  will  be  much  too  high.  The 
pulverization  may  be  satisfactorily  performed  by  grinding  with  ether,  as  described 
under  10,  treating  the  extracted  residue  with  the  hot  1.25%  sulphuric  acid  and 
proceeding  from  this  point  as  directed  above. 

327 


328  METHODS    OF   ANALYSIS  [Chap 

STARCH. 

10  Direct  Acid  Hydrolysis. —Tentative. 

Weigh  4  grams  of  the  sample,  if  unsweetened,  or  10  grams  if  sweetened,  into  a 
small  porcelain  mortar,  add  25  cc.  of  ether  and  grind.  After  the  coarser  materia) 
has  settled,  decant  the  ether,  together  with  the  fine  suspended  matter,  onto  an  11 
cm.  paper  of  sufficiently  fine  texture  to  retain  the  crude  starch.  Repeat  this  treat- 
ment until  no  more  coarse  material  remains.  After  the  ether  has  evaporated  from 
the  filter,  transfer  the  fat-free  residue  to  the  mortar  by  means  of  a  jet  of  cold  water 
and  rub  to  an  even  paste,  filtering  on  the  paper  previously  employed.  Repeat  this 
process  until  all  the  sugar  is  removed.  In  the  case  of  sweetened  products  the  fil- 
trate should  measure  at  least  500  cc.  Determine  crude  starch  in  the  extracted 
residue  as  directed  under  VIII,  60. 

11  Diastase  Method. — Tentative. 

Remove  fat  and  sugar  from  4  grams  of  the  sample,  if  unsweetened,  or  10  grams  if 
sweetened,  as  directed  under  10.  Wash  carefully  the  wet  residue  into  a  beaker  with 
100  cc.  of  water,  heat  to  boiling  over  asbestos  with  constant  stirring  and  continue 
the  boiling  and  stirring  for  30  minutes.  Replace  the  water  lost  by  evaporation  and 
immerse  the  beaker  in  a  water  bath  kept  at  55°-60°C.  When  the  liquid  has  cooled 
to  the  temperature  of  the  bath,  add  20  cc.  of  freshly  prepared  malt  extract  [VIII, 
61]  and  digest  the  mixture  for  2  hours  with  occasional  stirring.  Boil  a  second 
time  for  30  minutes,  dilute,  cool  and  digest  as  before  with  another  20  cc.  portion 
of  the  malt  extract.  Heat  again  to  boiling,  cool  and  transfer  to  a  250  cc.  flask.  Add 
3  cc.  of  alumina  cream,  make  up  to  the  mark  and  filter  through  a  dry  paper.  The 
residue  on  the  paper  should  show  no  signs  of  starch  when  examined  microscopically. 
Continue  from  this  point  as  directed  under  VIII,  62,  beginning  with  the  words 
"Place  200  cc.  of  the  filtrate  in  a  flask  with  20  cc.  of  hydrochloric  acid". 

12  FAT.-TENTATIVE. 

Dry  2  grams  of  the  material  over  sulphuric  acid  until  all  the  moisture  is  practi- 
cally removed.  (Products  rich  in  fat  show  a  tendency  to  cake  at  the  temperature 
of  boiling  water.  Hence,  drying  by  means  of  heat  must  be  avoided.)  Extract  with 
anhydrous  ether  in  a  continuous  extractor  until  no  more  fat  is  removed.  Grind 
and  repeat  the  extraction.  Introduce  the  ether  extract  into  a  tared  dish,  allow  the 
ether  to  evaporate  and  dry  the  residue  to  constant  weight  at  100°C. 

The  rapid  centrifugal  method^,  though  useful  and  accurate  under  ordinary  con- 
ditions, is  unreliable  during  the  summer  months  or  in  warm  latitudes  and  has  not 
been  approved. 

13  FAT  CONSTANTS.-TENTATIVE. 

Separate  the  fat  in  a  manner  similar  to  that  described  under  1 5  and  determine 
the  melting  point,  index  of  refraction,  iodin  absorption,  saponification,  Reichert- 
Meissl  and  Polenske  numbers  as  directed  under  XXIII.  Melting  point  determi- 
nations upon  this  material  do  not  become  normal  until  the  fat  has  been  kept  for  at 
least  24  hours  in  a  cool  place. 

1  4  MILK  FAT  IN  MILK  CHOCOLATE.-TENTATIVE. 

Estimate  the  amount  of  milk  fat  in  milk  chocolate  from  the  following  formula 
based  on  a  Reichert-Meissl  number  of  0.5  for  cocoa  butter: 


XXV]  CACAO   PRODUCTS  329 

^        24A  +  0.5B  .        ,  .  , 

C  =  :: in  which 

o 

A  =  grams  of  butter  fat  in  5  grams  of  mixed  fat; 

B  =  5  —  A  =  grams  of  cocoa  fat  in  5  grams  of  mixed  fat; 

C  =  Reichert-Meissl  number  of  extracted  fat. 

From  which  the 

Q  Q   c 

Weight  of  butter  fat  in  5  grams  of  mixed  fat  =  — j~-  and  the 

4.7 

Per  cent  of  butter  fat  =  per  cent  of  total  fat  X  — - — - 

23.5 

1  5  SUCROSE  AND  LACTOSE.— TENTATIVE. 

Prepare  the  sample  by  chilling  well  and  shaving  as  finely  as  possible  with  a  knife. 
Transfer  26  grams  of  this  material  to  an  8  ounce  nursing  bottle,  add  about  100  cc. 
of  petroleum  ether  and  shake  for  5  minutes.  Centrifugalize  until  the  solvent  is 
clear.  Draw  off  the  same  by  suction  and  repeat  the  treatment  with  petroleum 
ether.  Place  the  bottle  containing  the  de-fatted  residue  in  a  warm  place  until  the 
residual  traces  of  petroleum  ether  are  practically  expelled.  Add  100  cc.  of  water, 
shake  until  all  the  chocolate  is  loosened  from  the  sides  and  bottom  of  the  bottle 
and  then  shake  for  3  minutes  longer.  Add  basic  lead  acetate  solution  from  a  burette 
to  complete  precipitation,  then  sufficient  water  to  make  the  total  volume  of  liquid 
110  cc.  Mix  thoroughly  and  filter  through  a  folded  filter.  Make  the  direct  polari- 
scopic  reading  "a"  in  a  200  mm.  tube.  Precipitate  the  excess  of  lead  by  anhydrous 
potassium  oxalate  and  invert  the  solution  as  directed  under  VIII,  14.  Obtain 
the  reading  of  the  inverted  solution.  Multiply  the  invert  reading  by  2  to  correct 
for  dilution  "b".  From  the  figures  obtained  calculate  the  percentages  of  sucrose 
(S)  and  lactose  (L)  by  the  formulas 

(a-b)  (110 +  x) 


S  = 


<1-1  +  -Im)-s 


142.66-  I 


in  which  the  value  of  x  is  obtained  from 
0.79 

0.2244  fa-21d)       .        ,.,,,"  ,  ,  •      ^,   ■      ,  , 

in  which  the  value  of  d  is  obtained  from 


1  -  0.00204  (a  -  21dj 

J  ^        a— b 

142.66- 1 

1 6  CASEIN  IN  MILK  CHOCOLATE.-TENTATIVE. 

It  is  unnecessary  to  de-fat  the  chocolate.  Weigh  10  grams  of  the  chocolate 
into  a  .500  cc.  Erlenmeyer  flask  and  add  250  cc.  of  1%  sodium  oxalate  solution.  Heat 
to  boiling  and  boil  gently  for  a  few  minutes,  then  cool,  add  5  grams  of  magnesium 
carbonate  and  filter.  Determine  nitrogen  in  50  cc.  of  this  filtrate.  Pipette  100  cc. 
of  the  filtrate  into  a  200  cc.  volumetric  flask  and  dilute  almost  to  the  mark  with 
water.  Then  precipitate  the  casein  by  the  addition  of  2  cc.  of  glacial  acetic  acid 
or  1  cc.  of  concentrated  sulphuric  acid.  Make  to  volume,  shake,  filter  and  deter- 
mine nitrogen  in  100  cc.  of  the  filtrate.  The  difference  between  the  2  nitrogen  de- 
terminations gives  the  nitrogen  derived  from  the  casein  which,  multiplied  by  6.38, 
gives  the  amount  of  casein  present  in  2  grams  of  the  sample. 


330  METHODS    OF  ANALYSIS 

1 7  COLORING  MATTERS.-TENTATIVE. 

Proceed  as  directed  under  XI. 

BIBLIOGRAPHY. 
1  U.  S.  Bur.  Chem.  Bull.  137,  p.  103. 


XXVI.     COFFEES. 
GREEN  COFFEE. 

1  MACROSCOPIC  EXAMINATION.-TENTATIVE. 

A  macroscopic  examination  is  usually  sufficient  to  show  the  presence  of  excessiv  ■ 
amounts  of  black  and  blighted  coffee  beans,  coffee  hulls,  stones  and  other  foreign 
matter.    These  can  be  separated  by  hand  picking  and  determined  gravimetrically. 

2  COLORING  MATTERS.— TENTATIVE. 

Shake  vigorously  100  grams  or  more  of  the  sample  with  cold  water  or  70%  alco- 
hol by  volume.  Strain  through  a  coarse  sieve  and  allow  to  settle.  Identify 
soluble  colors  in  the  solution  and  insoluble  pigments  in  the  sediment  as  directed 
under  XI. 

ROASTED  COFFEE. 

3  MACROSCOPIC  EXAMINATION.-TENTATIVE. 

Artificial  coffee  beans  are  apparent  from  their  exact  regularity  of  form.  Roasted 
legumes  and  lumps  of  chicory,  when  present  in  whole  roasted  coffee,  can  be  picked 
out  and  identified  microscopically.  In  the  case  of  ground  coffee  sprinkle  some  of 
the  sample  on  cold  water  and  stir  lightly.  Fragments  of  pure  coffee,  if  not  over- 
roasted, will  float,  while  fragments  of  chicory,  legumes,  cereals,  etc.,  will  sink  imme- 
diately, chicory  coloring  the  water  a  decided  brown.  In  all  cases  identify  the  par- 
ticles that  sink,  by  microscopical  e.xamination. 

4  PREPARATION  OF  SAMPLE.— TENTATIVE. 

Grind  the  sample  and  pass  through  a  sieve  having  holes  0.5  mm.  in  diameter 
and  preserve  in  a  tightly  stoppered  bottle. 

5  MOISTURE.-TENTATIVE. 

Dry  5  grams  of  the  simple  at  105°-110°C.  for  5  hours  and  subsequent  periods  of 
an  hour  each  until  constant  weight  is  obtained.  The  same  procedure  may  be  used, 
drying  in  vacuo  at  the  temperature  of  boiling  water.  In  the  case  of  whole  coffee, 
grind  rapidly  to  a  coarse  powder  and  weigh  at  once  portions  for  the  determina- 
tion without  sifting  and  without  unnecessary  exposure  to  the  air. 

SOLUBLE  SOLIDS. 

6  Winion  Method. — Tentative. 

Place  4  grams  of  the  sample  in  a  200  cc.  flask,  add  water  to  the  mark  and  allow 
the  mass  to  infuse  8  hours,  with  occasional  shaking;  let  stand  16  hours  long  r  with- 
out shaking,  filter,  evaporate  50  cc.  of  the  filtrate  to  dryness  in  a  flat-bottomed 
dish,  dry  at  100°C.  and  weigh. 

7  ASH.-OFFICIAL. 
Proceed  as  directed  under  VIII,  4. 

331 


332  METHODS    OF   ANALYSIS  [Chap. 

8  ASH  INSOLUBLE  IN  ACID.^TENTATIVE. 

Proceed  as  directed  under  XXIV,  5. 

9  SOLUBLE  AND  INSOLUBLE  ASH.— TENTATIVE. 
Proceed  as  directed  under  K,  17. 

10  ALKALINITY  OF  THE  SOLUBLE  ASH.— TENTATIVE. 
Proceed  as  directed  under  IX,  18. 

1 1  SOLUBLE  PHOSPHORIC  ACID  IN  THE  ASH.-TENTATIVE. 

Acidify  the  solution  of  soluble  ash,  obtained  in  9,  with  dilute  nitric  acid  and 
determine  phosphoric  acid  (PaOjjas  directed  under  I,  6  or  9. 

12  INSOLUBLE  PHOSPHORIC  ACID  IN  THE  ASH.-TENTATIVE. 
Determine  phosphoric  acid  (P2O6)  in  the  insoluble  ash  as  directed  under  I,  6 

or  9. 

13  CHLORIN.-OFFICIAL. 
Proceed  as  directed  under  III,  18. 

CAFFEIN. 

14  Gorter  Method^. — Tentative. 

Moisten  11  grams  of  finely  powdered  coffee  with  3  cc.  of  water,  allow  to  stand 
30  minutes  and  extract  with  chloroform  for  3  hours  in  a  Soxhlet  extractor.  Evap- 
orate the  extract,  treat  the  residue  of  fat  and  caffein  with  hot  water,  filter  through 
a  cotton  plug  and  moistened  filter  paper  and  wash  with  hot  water.  Make  up  the 
filtrate  and  washings  to  55  cc,  pipette  off  50  cc.  and  extract  4  times  with  chloro- 
form. Evaporate  the  chloroform  extract  in  a  tared  flask,  dry  the  caffein  at  100°C. 
and  weigh.  Transfer  the  residue  to  a  Kjeldahl  flask  with  a  small  amount  of  hot 
water  and  determine  nitrogen  as  directed  in  I,  18,  21  or  23.  To  obtain  the  weight 
of  caffein  multiply  the  result  by  3.464. 

1 5  Modified  Stahlschmidt  Method^. — Tentative. 

Weigh  3.125  grams  of  the  finely  powdered  sample  into  a  500  cc.  flask,  add  225  cc. 
of  water  (this  volume  will  shrink  to  about  200  cc.  by  boiling),  attach  a  reflux  con- 
denser and  boil  for  2  hours.  Add  2  grams  of  dry  basic  lead  acetate  [VIII,  13  (C)] 
and  boil  10  minutes  more.  Cool,  transfer  to  a  250  cc.  graduated  flask,  fill  to  the 
mark,  filter  through  a  dry  filter,  measure  200  cc.  of  the  filtrate  into  a  250  cc. 
graduated  flask  and  pass  hydrogen  sulphid  through  it  to  remove  the  e.xcess  of  lead. 
Make  the  solution  up  to  the  mark  and  filter  through  a  dry  filter.  Measure  200  cc. 
of  this  filtrate  into  an  evaporating  dish  and  concentrate  to  about  40  cc.  Wash  the 
concentrated  solution  with  as  little  water  as  possible  into  a  small  separatory  funnel 
and  shake  out  4  times  with  chloroform,  using  25,  20,  15  and  10  cc,  respectively.  If 
any  emulsion  forms,  break  it  up  with  a  stirring  rod  and  run  the  separated  portions  of 
chloroform  through  a  5  cm.  filter  paper  into  a  small,  tared  Erlenmeyer  flask.  Evap- 
orate off  the  chloroform  on  the  steam  bath,  or  recover  the  chloroform  by  attaching 
the  flask  to  a  condenser  and  distilling  to  a  small  volume.  Dry  the  fine,  white  crystals 
of  caffein  to  constant  weight  at  75°C.  Test  the  purity  of  this  residue  by  deter- 
mining nitrogen  as  directed  in  I,  18,  21  or  23  and  multiplying  by  the  factor  3.464. 


XXVI]  COFFEES  333 

'Ig  CRUDE  FIBER.— TENTATIVE. 

Proceed  as  directed  under  VIII,  68. 
IJ  STARCH.-TENTATIVE. 

Extract  5  grams  of  the  finely  pulverized  sample  on  a  hardened  filter  with  5  suc- 
cessive portions  (10  cc.  each)  of  ether;  wash  with  smalljportions^of  95%  alcohol 
by  volume  until  a  total  of  200  cc.  have  passed  through,  place  the  residue  in  a 
beaker  and  proceed  as  directed  under  VIII,  62. 

1 8  SUGARS.— TENTATIVE. 
Proceed  as  directed  under  VIII,  58  and  59. 

19  PETROLEUM  ETHER  EXTRACT.-TENTATIVE. 

Dry  2  grams  of  the  coffee  at  100°C.,  extract  with  petroleum  ether  (b.  p.  35°-50°C.) 
for  16  hours,  evaporate  the  solvent,  dry  the  residue  at  100°C.  and  weigh. 

20  TOTAL  ACIDITY.-TENTATIVE. 

Treat  10  grams  of  the  sample,  prepared  as  directed  under  4, 'with  75  cc.  of  80% 
alcohol  by  volume  in  an  Erlenmeyer  flask,  stopper  and  allow  to  stand  16  hours, 
shaking  occasionally.  Filter  and  transfer  an  aliquot  of  the  filtrate  (25  cc.  in  the 
case  of  green  coffee,  10  cc.  in  the  case  of  roasted  coffee)  to  a  beaker,  dilute  to  about 
100  cc.  with  water  and  titrate  with  N/10  alkali,  using  phenolphthalein  as  an  indi- 
cator. Express  the  result  as  the  number  of  cc.  of  N/10  alkali  required^to  neutralize 
the  acidity  of  100  grams  of  the  sample. 

21  VOLATILE  ACIDITY.-TENTATIVE. 

Into  a  volatile  acid  apparatus  [XVI,  27;  Fig.  8]  introduce  a  few  glass  beads  and 
over  these  place  20  grams  of  the  unground  sample.  Add  100  cc.  of  recentlj'  boiled 
water  to  the  sample,  place  a  sufficient  quantity  of  recently  boiled  water  in  the  outer 
flask  and  distil  until  the  distillate  is  no  longer  acid  to  litmus  paper  (usually  100  cc. 
of  distillate  will  be  collected).  Titrate  the  distillate  with  N/10  alkali,  using  phenol- 
phthalein as  an  indicator.  Express  the  result  as  the  number  of  cc.  of  N/10  alkali 
required  to  neutralize  the  acidity  of  100  grams  of  the  sample. 

COATING  AND  GLAZING  SUBSTANCES. 

22  SUGAR  AND  DEXTRIN.— TENTATIVE. 

Introduce  100  grams  of  the  whole  coffee  into  a  beaker,  add  exactly  300  cc.  of 
water,  stir  and  allow  to  stand  5  minutes,  with  frequent  stirring.  Filter  through  a 
dry  paper,  add  carefully  to  the  filtrate  sufficient  dry  lead  acetate  to  precipitate 
all  the  caffetannic  acid,  avoiding  an  excess.  Filter  through  dry  paper  and  re- 
move the  lead  from  the  filtrate  by  the  addition  of  a  slight  excess  of  anhydrous 
potassium  oxalate.  Filter  through  a  dry  paper  and  determine  reducing  sugars  as 
invert  sugar  in  50  cc.  of  the  filtrate,  as  directed  in  VIII,  25.  Invert  a  75  cc.  aliquot 
of  the  filtrate  as  directed  under  VIII,  14.  Cool,  nearly  neutralize  with  sodium 
hydroxid  solution,  make  up  to  100  cc.  and  determine  reducing  sugars  as  invert  sugar 
in  the  resulting  solution,  as  directed  under  VIII,  25.  Measure  a  100  cc.  aliquot 
of  the  filtrate  into  a  200  cc.  flask,  add  10  cc.  of  25%  hydrochloric  acid  and  hy- 
drolyze  as  directed  under  VlII,  60.  Cool,  neutralize  with  sodium  hydroxid  solu- 
tion, make  up  to  volume,  filter  through  a  dry  paper  and  determine  reducing  sugars 
as  invert  sugar  in  50  cc.  of  the  filtrate  as  directed  under  VIII,  25.     Calculate  the 


334  METHODS   OF  ANALYSIS 

reducing  sugars  in  each  instance  to  per  cent  by  weight  of  the  original  coffee.  Cal- 
culate sucrose  from  the  reducing  sugars  before  and  after  inversion  as  directed  in 
VIII,  18,  and  calculate  dextrin  as  follows:  Subtract  the  reducing  sugars  after  in- 
version from  the  reducing  sugars  after  hydrolysis,  multiply  the  difference  by  the 
factor  0.9561  to  convert  the  result  to  dextrose  and  then  by  0.9  to  convert  to  dextrin. 
In  some  instances  the  presence  of  sucrose  in  the  water  extract  may  be  verified 
by  polarization.  The  presence  of  dextrin  in  the  water  extract  may  be  verified  by 
polarization  as  directed  under  IX,  25,  and  by  the  erythro-dextrin  test  [IX,  47] 
performed  on  the  water  extract  previous  to  clarification  with  lead  acetate. 

23  EGG  ALBUMEN  AND  GELATIN.— TENTATIVE. 

Treat  100  grams  of  the  whole  coffee  with  500  cc.  of  water  and  allow  to  stand  with 
frequent  stirring  for  5  minutes.  Filter  and  treat  separate  portions  of  the  filtrate 
with  (1)  a  strong  solution  of  tannic  acid;  (2)  Millon's  reagent  [XV,  9];  (3)  by 
boiling.  In  the  presence  of  egg  albumen  a  more  or  less  heavy  precipitate  will 
be  formed  in  each  case.  As  a  confirmatory  test,  treat  an  aliquot  of  the  filtrate  with 
an  excess  of  tannic  acid  solution,  add  a  little  salt  if  necessary  to  secure  flocculation 
of  the  precipitate,  filter  and,  without  washing,  introduce  the  paper  and  its  con- 
tents into  a  Kjeldahl  flask  and  determine  nitrogen.  By  this  method  coffee  not 
coated  with  albumen  or  gelatin  will  yield  less  than  10  mg.  of  nitrogen  per  100  grams 
of  sample. 

24  CHICORY  INFUSION.-TENTATIVE, 

Cover  100-150  grams  of  the  whole  coffee  with  water,  allow  to  soak  2-3  minutes, 
stirring  frequently,  and  drain  the  aqueous  washings  through  a  coarse  sieve.  Wash 
the  coffee  upon  the  sieve  with  about  100  cc.  of  water  and  centrifugalize  the  com- 
bined washings.  Decant  the  clear  liquid  from  the  sediment,  drain  almost  dry  upon 
filter  paper,  then  mount  the  sediment  in  chloral  hydrate  [XXTV,  20  (f )]  and  exam- 
ine under  the  microscope  for  elements  of  chicory. 

FATS  AND  WAXES, 

25  Spath  Method^.— Tentative. 

Treat  100-200  grams  of  the  beans  with  low  boiling  petroleum  ether  for  10  min- 
utes, pour  off  the  petroleum  ether  and  repeat  the  process.  Filter  the  combined 
petroleum  ether  extracts,  evaporate  and  determine  the  index  of  refraction  and  the 
saponification  number  of  the  residue,  as  directed  under  XXIII,  6  and  20. 

BIBLIOGRAPHY. 
lAnn.,  1908,  358:327. 

2  Allen.     Commercial  Organic  Analysis.     4th  ed.,  1909-14,  6:  607. 

3  Forschb.  uber  Lebensm.,  1895,  2:  223. 


XXVII.    TEA. 

1  DUST,  STEMS  AND  FOREIGN  LEAVES.— TENTATIVE. 

Place  1  gram  of  the  tea  in  a  300  cc.  casserole,  add  200  cc.  of  boiling  water  and 
allow  to  stand  15  minutes.  This  treatment  will  cause  the  leaves  to  unroll,  and  a 
macroscopic  examination  will  reveal  the  presence  or  absence  of  dust  or  stems,  while 
the  leaves  will  be  in  condition  for  examination  as  to  their  form  and  structure'. 

2  PREPARATION  OF  SAMPLE.-TENTATIVE. 

Grind  the  sample  and  pass  it  through  a  sieve  having  circular  openings  0.5  mm. 
in  diameter. 

3  MOISTURE.— TENTATIVE. 
Proceed  as  directed  under  IX,  2. 

4  WATER  EXTRACT=.-TENTATIVE. 

To  2  grams  of  the  original  sample  in  a  500  cc.  Erlenmeyer  flask  add  200  cc.  of  hot 
water  and  boil  over  a  low  flame  for  an  hour.  The  flask  should  be  closed  with  a  rub- 
ber stopper  through  which  passes  a  glass  tube  18  inches  long  for  a  condenser.  The 
loss  from  evaporation  should  be  replaced  from  time  to  time  by  the  addition  of 
hot  water.  Filter  through  a  tared  filter  and  wash  the  residue  until  the  filtrate  meas- 
ures 500  cc,  stirring  the  contents  of  the  filter  throughout  the  process  to  facilitate 
the  filtering.  Dry  the  filter  paper  and  residue  in  the  funnel  in  the  steam  oven  until 
the  excess  of  water  is  removed,  transfer  paper  and  contents  to  a  tared  weighing 
bottle  and  dry  to  constant  weight  at  100°C. 

5  ASH.-OFFICIAL. 

Proceed  as  directed  under  VIII,  4. 

6  SOLUBLE  AND  INSOLUBLE  ASH.— TENTATIVE. 
Proceed  as  directed  under  IX,  17. 

7  ASH  INSOLUBLE  IN  ACID.— TENTATIVE. 

Proceed  as  directed  under  XXIV,  5. 

8  ALKALINITY  OF  THE  ASH.-TENTATIVE. 

Determine  the  alkalinitv  of  the  soluble  and  insoluble  ash  as  directed  under  IX, 
18  and  19. 

9  PHOSPHORIC  ACID  IN  THE  ASH.-TENTATIVE. 

Determine  phosphoric  acid  fPjOs)  in  the  soluble  and  insoluble  ash  as  directed 
under  XXVI,  11  and  12. 

10  PETROLEUM  ETHER  EXTRACT.-TENTATIVE. 
Proceed  as  directed  under  XXVI,  19. 


336  METHODS    OF   ANALYSIS  [Chap. 

11  PROTEIN. -TENTATIVE. 

Determine  nitrogen  as  directed  under  I,  18,  21  or  23.  Subtract  the  percentage 
of  nitrogen  present  as  caffein  from  the  percentage  of  total  nitrogen  to  obtain  the 
percentage  of  nitrogen  present  as  protein.  Multiply  this  result  by  6.25  to  obtain 
the  percentage  of  protein. 

12  CRUDE  FIBER.— TENTATIVE. 
Proceed  as  directed  under  VIII,  68. 

13  VOLATILE  OIL.— TENTATIVE. 

Add  100  grams  of  tea  to  800  cc.  of  water,  distil,  extract  the  distillate  several  times 
with  petroleum  ether,  transfer  the  combined  petroleum  ether  extracts  to  a  tared 
dish,  evaporate  at  room  temperature,  dry  in  a  desiccator  and  weigh. 

CAFFEIN. 

14  Modified  Stahlschmidt  Method. — Tentative. 
Proceed  as  directed  under  XXVI,  15. 


Proctor  Modification  of  the  Lowenthal  Method^. — Tentative. 

1 5  REAGENTS  . 

(a)  Potassium  permanganate  solution. — Make  up  a  solution  containing  1.33  grams 
per  liter  and  obtain  its  equivalent  in  terms  of  N/10  oxalic  acid. 

(b)  N/IO  oxalic  acid. 

(C)  Indigo  carmine  solution. — Make  up  a  solution  containing  6  grams  of  indigo 
carmine  (free  from  indigo  blue)  and  50  cc.  of  concentrated  sulphuric  acid  per  liter. 

(d)  Gelatin  solution. — Soak  25  grams  of  gelatin  for  an  hour  in  saturated  sodium 
chlorid  solution,  heat  until  the  gelatin  is  dissolved  and  make  up  to  1  liter  after 
cooling. 

(e)  Acid  sodium  chlorid  solution. — ^Acidify  975  cc.  of  saturated  sodium  chlorid  solu- 
tion with  25  cc.  of  concentrated  sulphuric  acid. 

(f )  Powdered  kaolin. 


DETERMINATION. 


16 

Boil  5  grams  of  the  tea  for  30  minutes  with  400  cc.  of  water;  cool,  transfer  to  a 
500  cc.  graduated  flask  and  make  up  to  the  mark.  To  10  cc.  of  the  infusion,  filtered 
if  not  clear,  add  25  cc.  of  the  indigo  carmine  solution  and  about  750  cc.  of  water. 
Add  from  a  burette  the  potassium  permanganate  solution,  a  little  at  a  time  while 
stirring,  until  the  color  becomes  light  green,  then  drop  by  drop,  until  the  color 
changes  to  bright  yellow  or  to  a  faint  pink  at  the  rim.  Designate  the  number  of 
cc.  of  permanganate  used  as  "a". 

Mix  100  cc.  of  the  clear  infusion  of  tea  with  50  cc.  of  the  gelatin  solution,  100  cc. 
of  the  acid  sodium  chlorid  solution  and  10  grams  of  the  powdered  kaolin,  and  shake 
several  minutes  in  a  stoppered  flask.  After  settling  decant  through  a  filter.  Mix 
25  cc.  of  the  filtrate  with  25  cc.  of  the  indigo  carmine  solution  and  about  750  cc.  of 
water  and  titrate  with  permanganate  as  before.  The  number  of  cc.  of  permanganate 
used  subtracted  from  that  obtained  above,  "a",  gives  the  amount  of  permanganate 
required  to  oxidize  the  tannin.  One  cc.  of  N/10  oxalic  acid  is  equivalent  approxi- 
mately to  0.004157  gram  of  tannin  (gallotannic  acid). 


XXVn]  TEA  337 

Facing. 

17  general.— tentative. 

Mineral  pigments  may  be  detected  in  the  ash,  or  the  tea  may  be  shaken  up  with 
a  large  volume  of  water,  and  the  water  separated  from  the  leaves  by  a  sieve,  when 
the  insoluble  mineral  substances  used  in  facing  will  settle  and  can  be  removed  by 
filtration  for  further  examination,  as  directed  under  XI,  1 ,  the  catechu  and  other 
soluble  substances  being  in  the  filtrate. 

18  PARAFFIN  AND  WAXY  SUBSTANCES.— TENTATIVE. 

Spread  a  quantity  of  the  tea  between  2  sheets  of  unglazed,  white  paper  and  place 
thereon  a  hot  iron.     Any  greasy  substance  will  stain  the  paper*. 

PIGMENTS  USED  FOR  COLORING  OR  FACING. 

19  Read  Method^.— Tentative. 

Place  60  grams  of  the  tea  in  a  60  mesh,  5-6  inch  sieve,  provided  with  a  top.  Sift 
a  small  quantity  (approximately  0.1  gram)  of  the  dust  upon  a  piece  of  semi-glazed, 
white  paper  about  8  by  10  inches.  To  obtain  the  requisite  amount  of  dust,  it  is 
sometimes  necessary  to  rub  the  leaf  gently  against  the  bottom  of  the  sieve,  but  this 
must  not  be  done  until  the  sieve  has  been  well  shaken  over  the  paper.  Place  the 
paper  on  a  plain,  firm  surface,  preferably  glass  or  marble,  and  crush  the  dust  by 
pressing  firmly  upon  it  a  flat  steel  spatula  about  5  inches  long.  Repeat  the  crush- 
ing process  until  the  tea  dust  is  ground  almost  to  a  powder  when  particles  of  color- 
ing matter,  if  present,  become  visible  as  streaks  on  the  paper.  Brush  off  the 
loose  dust  and  examine  the  paper  by  means  of  a  simple  lens  magnifying  7h  diame- 
ters. In  distinguishing  these  particles  and  streaks  bright  light  is  essential.  In 
many  cases  the  character  of  the  pigment  is  indicated  by  the  behavior  of  these 
streaks  when  treated  with  reagents  and  examined  under  a  microscope.  The 
crushed  particles  of  natural  leaf  in  either  black  or  green  tea  appear  in  such 
quantity  that  there  is  no  chance  of  mistaking  them  for  coloring  or  facing  material. 
This  test  should  be  repeated  using  black,  semi-glazed  paper  for  facings  such  as  talc, 
gypsum,  barium  sulphate  or  clay. 

BIBLIOGRAPHY. 

1  U.  S.  Bur.  Chem.  Bull.  13  (VII);  Villiers  and  Colin.  Trait6  des  Alterations  et 
Falsifications  des  Substances  Alimentaires.     2nd  ed.,  190&-11. 

2  U.  S.  Bur.  Chem.  Bull.  105,  p.  48. 
'  Ibid.,  13  (VII),  p.  890. 

*U.  S.  Treas.  Dept.,  T.  D.  35244.  March  23,  1915. 

*  Ibid.;  Proc.  Eighth  Intern.  Cong.  Appl.  Chem.,  1912,  18:  301. 


XXVIII.     BAKING  POWDERS  AND  THEIR  INGREDIENTS. 

1  PREPARATION  OF  SAMPLE.— TENTATIVE. 

Remove  the  entire  sample  from  the  package,  mi.x  carefully  and  pass  through  a 
20-40  mesh  sieve. 

TOTAL  CARBON  DIOXID. 

2  General  Method. — Tentative. 

Make  the  determination  by  the  absorption  method,  employing  any  apparatus 
which  gives  accurate  results  when  checked  with  pure  calcite.  Whatever  appara- 
tus is  chosen,  the  tubes  and  materials  used  for  absorbing  and  drying  the  carbon 
dioxid  may  be  varied  according  to  the  preference  of  the  analyst.  Use  0.25-1  gram 
of  sodium  or  calcium  carbonate,  according  to  the  amount  of  absorbent  employed, 
and  in  the  case  of  baking  powder  0.50-2  grams. 

Method  Using  Knorr's  Apparatus. — Tentative. 

3  REAGENTS. 

(a)  50%  potassium  liydroxid  solution. 

(b)  Soda  lime. — Finely  granulated  and  freed  from  dust  by  sifting. 

4  APPARATUS. 


FIG.  14    KNORR'S  APPARATUS  FOR  THE  DETERMIMATION  OF  CARBON  DIOXID. 

This  consists  of  a  flask  (.4),  fitted  by  means  of  a  ground-glass  joint  with  a  glass 
connection  through  the  upjjer  part  of  which  passes  a  dropping  funnel  (ZJ),  and 
joined  at  the  side  with  a  Liebig  condenser  (D).     The  mouth  of  the  dropping  funnel 

339 


340  METHODS    OF   ANALYSIS  [Chap. 

(B)  is  connected  by  means  of  a  perforated  stopper  with  a  soda  lime  tube  (C).  The 
upper  end  of  the  Liebig  condenser  is  connected  by  a  rubber  joint  with  a  Geissler 
bulb  (E),  containing  sulphuric  acid  for  drying  the  gas  passing  into  the  next  Geissler 
bulb  (F),  connected  with  (E),  and  containing  strong  potassium  hydroxid  solution 
(1  to  2).  The  bulb  (F)  is  connected  with  a  third  Geissler  bulb  (G),  containing  sul- 
phuric acid  for  the  absorption  of  moisture  escaping  from  F.  A  fourth  Geissler 
bulb  {H)  is  attached  to  G  as  a  precaution  to  prevent  moisture  from  the  air  being 
absorbed  by  G.  H  is  connected  with  an  aspirator.  Many  analysts  prefer  to  re- 
place the  bulb  (F)  by  2  U-tubes  filled  with  sifted  soda  lime. 

5  DETERMINATION. 

Place  0.5-2  grams  of  the  baking  powder,  the  amount  depending  upon  the  per- 
centage of  carbon  dioxid  present,  in  the  flask  (A),  which  must  be  perfectly  dry. 
Close  the  flask  with  the  stopper  which  carries  the  funnel  tube  and  the  tube  con- 
necting with  the  absorption  apparatus.  Weigh  separately  the  Geissler  bulbs  (F) 
and  ((?)  and  attach  them  to  the  apparatus.  If  2  soda  lime  tubes  are  employed, 
weigh  them  separately  and  fill  the  first  anew  when  the  second  increases  materially 
in  weight.  Nearly  fill  the  funnel  tube  (B)  with  hydrochloric  acid  (sp.  gr.  1.1)  and 
place  the  soda  lime  tube  (C)  in  position.  Then  aspirate  air  through  the  Geissler 
bulbs  at  a  rate  of  about  2  bubbles  per  second.  Open  the  stopper  of  the  funnel  and 
allow  the  acid  to  run  slowly  into  the  flask,  care  being  taken  that  the  evolution  of 
gas  be  so  gradual  as  not  to  materially  increase  the  current  through  the  Geissler 
bulbs.  After  all  the  acid  has  been  introduced,  close  the  stop-cock  in  B,  continue 
the  aspiration  and  heat  gradually  the  contents  of  the  flask  to  boiling.  While  the 
flask  is  being  heated  the  aspirator  tube  may  be  removed,  although  many  analysts 
prefer,  when  using  ground-glass  joints,  to  aspirate  during  the  entire  operation. 
Continue  the  boiling  for  a  few  minutes  after  the  water  has  begun  to  condense  in 
D,  then  remove  the  flame,  open  the  stop-cock  in  tube  (B)  and  allow  the  apparatus 
to  cool  with  continued  aspiration.  Remove  the  absorption  bulbs  (F)  and  (G)  and 
weigh.     The  increase  in  weight  is  due  to  carbon  dioxid. 

Method  Using  Heidenhain's  Apparatus. — Tentative. 

6  REAGENTS. 

(a)  Calcium  chlorid.— Use  calcium  chlorid  dehydrated  at  200°C.,  but  not  fused. 
Grind  it  coarsely  in  a  coffee  mill  and  sift  through  No.  18  wire  gauze  to  remove  the 
extremely  coarse,  and  through  No.  30  wire  gauze  to  remove  the  very  fine,  particles. 

(b)  Soda  lime. — Grind  and  sift  the  soda  lime^  for  the  weighed  tubes  as  described 
above.  It  should  not  be  too  dry,  as  it  must  not  absorb  moisture  to  a  greater  degree 
than  the  calcium  chlorid. 

7  APPARATUS^. 

This  consists  of  a  cylinder  (A),  -filled  with  soda  lime  to  remove  carbon  dioxid 
from  the  air  passing  through  the  apparatus.  A  thick  layer  of  cotton  at  the  upper 
end  prevents  soda  lime  dust  from  being  carried  over.  Connect  the  cylinder  (A) 
by  means  of  a  perforated  rubber  stopper  and  a  bent  glass  tube  having  a  stop-cock 
(B)  and  a  capillary  constriction  (C)  with  a  short  piece  of  rubber  tubing  to  which 
is  attached  a  short  piece  of  glass  tubing  (£'),  fitted  with  a  perforated  rubber  stopper. 
The  latter  fits  tightly  into  the  constriction  of  the  funnel  tube  (D).  The  funnel  of 
the  latter  is  cylindrical  in  shape,  f  inch  in  diameter  at  the  upper  end,  f  inch  at  the 
lower  end  and  4  inches  long,  the  rubber  stopper  of  E  fitting  into  the  constriction. 


XXVIII] 


BAKING    POWDERS 


341 


The  stem  of  the  funnel  tube  (/))  passes  through  a  doubly  perforated  rubber  stopper 
almost  to  the  bottom  of  the  evolution  flask  (F),  which  is  ordinarily  of  150  cc. 
capacity  but,  in  the  case  of  foaming  liquids,  may  hold  300  cc.  Through  the  second 
perforation  in  the  stopper  connect  the  evolution  flask  (F)  with  a  reflux  condenser 
(G),  consisting  of  a  j  inch  glass  tube  around  which  is  wound  a  small  lead  pipe  carry- 
ing a  current  of  cold  water.  To  the  upper  end  of  the  condenser  attach  a  U-tube 
containing  a  little  calciimi  chlorid  (to  be  renewed  when  it  has  liquefied)  to  retain  the 
bulk  of  the  moisture.  Connect  this  U-tube  with  a  second  U-tube  (//),  filled  with 
coarse  calcium  chlorid,  and  this  in  turn  with  a  third  U-tube  (K),  filled  at  /  with  a  3 
inch  column  of  pumice  stone  impregnated  with  copper  sulphate  and  completely  de- 
hydrated at  150°C.,  the  remainder  of  the  tube  being  filled  \vith  fine  calcium  chlorid. 
Connect  the  U-tube  (K)  with  a  bent  glass  tube  having  a  stop-cock  (L)  which  is 
closed  when  the  apparatus  is  not  in  use.  Next  attach  the  absorption  U-tubes  (M) 
and  (iV)  which  are  |  inch  in  diameter  and  5  inches  long,  the  first  filled  mainly  with 
soda  lime  but  containing  a  little  calcium  chlorid  at  the  end  where  the  air  current 


FIG.  15.    HEIDENHAIN'S  APPARATUS  FOR  THE  DETERMIN.VTION  OF 
CARBON  DIOXID. 


enters,  the  second  filled  one  half  with  soda  lime  and  one  half  with  calcium  chlorid, 
the  latter  being  placed  at  the  side  where  the  air  current  leaves.  Connect  A''  with 
a  guard  tube  (0),  filled  with  calcium  chlorid  on  the  side  toward  A^  and  with  soda 
lime  on  the  side  toward  P,  the  latter  being  a  small  U-tube  trapped  with  glycerol  to 
indicate  the  passage  of  the  air  current.  Connect  P  with  a  safety  bottle  (R),  to 
receive  any  water  which  may  be  sucked  back  from  the  aspirator,  and  connect  R 
with  the  aspirator  (S),  a  4  liter  Mariette  bottle. 

The  tubes  (M)  and  (N)  should  hold  about  20  grams,  making  the  capacity  of  M 
for  carbon  dioxid  almost  1  gram  and  that  of  N  for  moisture  0.2  gram.  M  should 
be  refilled  when  its  weight  has  increased  0.75  gram  and  A''  after  an  increase  of  0.1 
gram  in  weight. 

Use  the  best  grade  of  rubber  for  all  connections,  applying  a  trace  of  castor  oil 
as  a  lubricant.  For  connections  of  the  weighed  tubes  use  rubber  tubing  boiled  in 
weak  lye,  washed  and  dried.  Apply  also  a  little  castor  oil,  which  is  thoroughly 
wiped  off  again  before  connecting  the  tubing. 

Before  using  the  apparatus  fill  H  and  K  with  carbon  dioxid  in  order  to  saturate 
the  alkalinity  of  the  calcium  chlorid  and  exhaust  after  several  hours. 


342  METHODS    OF   ANALYSIS  [Chap. 

8  DETERMINATION. 

In  order  to  find  the  allowable  rapidity  of  the  air  current  employed  during  the 
determination,  proceed  as  follows:  Charge  the  apparatus  exactly  as  for  an  analysis 
leaving  out  the  carbonate.  Begin  to  aspirate  at  the  rate  of  about  50  cc.  per  minute. 
After  2  liters  have  been  aspirated  weigh  the  tubes,  M  and  N.  If  they  have  lost  in 
weight,  repeat  the  experiment  with  40  cc.  per  minute,  and  so  on  until  the  weight  of 
the  tubes  remains  constant.  If  the  work  has  been  done  with  due  precaution,  the 
first  tube  should  have  lost  just  as  much  as  the  second  has  gained.  Do  not  exceed  the 
safe  speed  thus  found. 

Weigh  the  tubes  M  and  N  at  the  air  temperature  of  the  balance  room.  Shortly 
before  weighing  open  the  tubes  for  a  moment  to  allow  equalization  of  air.  Note 
the  thermometer  and  barometer  readings.  Connect  the  tubes  with  the  apparatus 
and  test  the  tightness  of  the  joints  by  closing  A  at  the  bottom,  opening  all  the  cocks, 
starting  the  aspirator,  and  observing  P,  in  which  the  liquid  should  soon  come  to  a 
standstill.  Then  disconnect  the  aspirator,  close  B,  remove  F,  put  in  the  substance, 
using  about  1  gram  of  sodium  carbonate  or  calcium  carbonate  or  about  2  grams  of 
baking  powder,  connect  F,  and  start  the  condenser  {G).  Introduce  50  cc.  of  10% 
hydrochloric  acid  through  D,  lifting  E  slightly  and  allowing  only  small  quantities 
of  the  dilute  acid  to  enter  at  a  time.  Light  the  burner  under  F,  heat  to  boiling 
and  reduce  the  flame  to  keep  the  liquid  just  at  the  boiling  point.  If  no  more  air 
passes  P,  start  the  aspiration.  When  the  water  stops  running  from  S,  open  B  care- 
fully and  adjust  the  outflow  of  the  aspirator  by  raising  or  lowering  the  syphon  to 
one  half  the  safe  speed. 

After  M  has  become  cool  increase  the  current  to  the  full  safe  speed  and  aspirate 
altogether  3  liters,  continuing  boiling  to  the  end  of  the  aspiration.  After  the  tubes 
have  assumed  the  temperature  of  the  balance  room,  open  for  a  moment  and  weigh. 
When  extreme  accuracy  is  desired,  note  again  the  thermometer  and  barometer 
readings  and  apply  correction  according  to  the  following  formula: 

-  (A2  -  Ai)  X  T  and  +  (B^  -  BO  X  B  in  which 

A^  =  the  temperature  at  first  weighing  in  degrees  C. ; 
A*  =  the  temperature  at  second  weighing  in  degrees  C; 
Bi  =  the  air  pressure  at  first  weighing  in  mm.; 
B''  =  the  air  pressure  at  second  weighing  in  mm.; 

T  and  B  are  constants  found  from  the  following  formulas: 

T  =  V  X  0.0000039  gram; 

B  =  V  X  0.0000015  gram  in  which 

0.0000039  =  change  in  weight  of  1  cc.  of  air  for  TC; 
0.0000015  =  change  in  weight  of  1  cc.  of  air  for  1  mm.  pressure; 

and  the  value  of  V  is  obtained  from 

2.7       2.0  8.5    ' 

representing  the  differential  volume  affected  by  temperature  and  pressure  and  being 
a  constant  for  the  tubes  and  in  which 


XXVIII]  BAKING    POWDERS  343 

G  =  the  weight  of  the  empty  tubes; 

F  =  the  weight  of  the  fillings; 
2.7  =  the  specific  gravity  of  glass; 
2.0  =  the  specific  gravity  of  filling; 
8.5  =  the  specific  gravity  of  brass; 

G         F 

— -  +  -—  =  volume  of  tubes  and  fillings; 

— -——  =  volume  of  brass  weights. 
0.5 

9  RESIDUAL  CARBON  DIOXIDE— TENTATIVE. 

Weigh  2  grams  of  the  baking  powder  into  a  flask  suitable  for  the  subsequent 
determination  of  carbon  dioxid,  add  20  cc.  of  cold  water  and  allow  to  stand  20  min- 
utes. Place  the  flask  in  a  metal  drying  cell  surrounded  by  boiling  water  and  heat, 
with  occasional  shaking,  for  20  minutes. 

To  complete  the  reaction  and  drive  off  the  last  traces  of  gas  from  the  semi-solid 
mass,  heat  quickly  to  boiling  and  boil  for  a  minute.  Aspirate  until  the  air  in  the 
flask  is  thoroughly  changed,  and  determine  the  residual  carbon  dioxid  by  absorption, 
as  directed  under  5  or  8. 

The  process  described^  based  on  the  methods  of  McGilH  and  Catlin^,  imitates 
as  far  as  practicable  the  conditions  encountered  in  baking  but  in  such  a  manner  that 
concordant  results  may  be  readily  obtained  on  the  same  sample  and  comparable 
results  on  different  samples. 

10  AVAILABLE  CARBON  DIOXID.— TENTATIVE. 
Subtract  the  residual  carbon  dioxid  from  the  total. 

1 1  ACIDITY.-TENTATIVE. 

(For  cream  of  tartar  and  its  substitutes.) 

Dissolve  1  gram  of  the  sample  in  hot  water  and  titrate  with  N/5  potassium  hy- 
droxid,  using  phenolphthalein  as  an  indicator. 

TARTARIC  ACID,  FREE  OR  COMBINED. 

12  Wolff  Method^— Tentative. 
(Applicable  in  the  presence  of  phosphates.) 

Shake  repeatedly  about  5  grams  of  the  sample  with  about  250  cc.  of  cold  water 
in  a  flask  and  allow  the  insoluble  portion  to  subside.  Decant  the  solution  through 
a  filter  and  evaporate  the  filtrate  to  dryness.  Powder  the  residue,  add  a  few  drops 
of  1%  resorcin  solution  and  about  3  cc.  of  strong  sulphuric  acid  and  heat  slowly. 
Tartaric  acid  is  indicated  by  a  rose-red  color  which  is  discharged  on  dilution  with 
water. 

TOTAL  TARTARIC  ACID. 

1 3  Goldenherg-Geromont-Heidenhain  Method. — Tentative. 
(Applicable  only  in  the  absence  of  aluminium  salts,  calcium  salts  and  phosphates.) 

Into  a  shalloAV  6  inch  porcelain  dish  weigh  out  2  grams  of  the  sample  and  suffi- 
cient potassium  carbonate  to  combine  with  all  the  tartaric  acid  not  in  the  form  of 
potassium  bitartrate.  '  Mix  thoroughly  with  15  cc.  of  cold  water  and  add  5  cc.  of 
99%  acetic  acid.  Stir  for  30  seconds  with  a  glass  rod  bent  near  the  end.  Add  100 
cc.  of  95%  alcohol,  stir  violently  for  5  minutes,  and  allow  to  settle  at  least  30  min- 


344  METHODS    OF   ANALYSIS  [Chap. 

utes.  Filter  on  a  Gooch  crucible  with  a  thin  layer  of  paper  pulp  and  wash  with  95% 
alcohol  until  2  cc.  of  the  filtrate  do  not  change  the  color  of  litmus  tincture  diluted 
with  water.  Place  the  precipitate  in  a  small  casserole,  dissolve  in  50  cc.  of  hot  water 
and  add  N/5  potassium  hydroxid,  leaving  it  still  strongly  acid.  Boil  for  a  minute. 
Finish  the  titration,  using  phenolphthalein  as  an  indicator  and  correct  the  reading 
by  adding  0.2  cc.  One  cc.  of  N/5  potassium  hydroxid,  under  the  above  conditions, 
is  equivalent  to  0.02641  gram  of  tartaric  anhydrid,  0.03001  gram  of  tartaric  acid, 
or  0.03763  gram  of  potassium  bitartrate.  Standardize  the  N/5  potassium  hydroxid 
by  means  of  pure  potassium  bitartrate. 

The  accuracy  of  this  method  is  indicated  by  the  agreement  of  the  percentages  of 
potassium  bitartrate  in  cream  of  tartar  powders  containing  no  free  tartaric  acid, 
obtained  by  calculation  from  the  tartaric  acid,  with  those  obtained  by  calculation 
from  the  potassium  oxid''. 

FREE  TARTARIC  ACID. 

14  Qualitative  Test. — Tentative. 

Extract  5  grams  of  the  sample  with  absolute  alcohol  and  evaporate  the  alcohol 
from  the  extract.  Dissolve  the  residue  in  dilute  ammonium  hydroxid,  transfer  to 
a  test  tube,  add  a  good  sized  crystal  of  silver  nitrate  and  heat  gently.  Tartaric 
acid  is  indicated  by  the  formation  of  a  silver  mirror.  If  desired,  the  absolute  alco- 
hol extract  may  be  tested  as  directed  under  1 2. 

15  Quantitative  Method. — Tentative. 

Calculate  the  percentage  of  tartaric  anhydrid  combined  with  the  potash  as  bi- 
tartrate, if  any,  and  subtract  this  from  the  percentage  of  total  tartaric  anhydrid. 
The  difference  is  the  tartaric  anhydrid  originally  added  as  the  free  acid,  although, 
if  the  sample  has  been  kept  for  a  long  time  or  has  been  improperly  stored,  a  portion 
or  all  of  this  acid  may  exist  at  the  time  of  analysis  as  the  sodimn  salt  resulting  from 
the  reaction  in  the  can  with  the  sodium  bicarbonate.  Multiply  by  1.137  to  obtain 
the  percentage  of  tartaric  acid. 

16  POTASSIUM  BITARTRATE.— TENTATIVE. 

If,  as  is  usually  the  case,  potassium  bitartrate  is  the  only  potassium  salt  present, 
multiply  the  percentage  of  total  potash,  determined  as  directed  under  24,  by  3.994. 

STARCH. 

17  Direct  Inversion  Method. — Tentative. 

(For  all  baking  powder  ingredients  free  from  lime.) 

Weigh  5  grams  of  the  powder  into  a  500  cc.  graduated  flask  and  proceed  as  directed 
under  VIII,  60. 

18  Indirect  Method^. — Tentative. 

(For  phosphate,  alum  phosphate  and  all  other  baking  powders  containing  lime.) 

Mix  5  grams  of  the  powder  with  200  cc.  of  3%  hydrochloric  acid  in  a  500  cc.  grad- 
uated flask  and  allow  the  mixture  to  stand  for  an  hour,  with  frequent  shaking. 
Filter  on  an  11  cm.  hardened  filter,  taking  care  that  a  clear  filtrate  is  obtained. 
Rinse  the  flask  once  without  attempting  to  remove  all  the  starch,  and  wash  the 
paper  twice  with  cold  water.  Carefully  wash  the  starch  from  the  paper  back  into 
the  flask  with  200  cc.  of  water.  Add  20  cc.  of  25%  hydrochloric  acid  and  proceed  as 
directed  under  VIII,  60. 


XXVIII]  BAKING    POWDERS  345 

The  treatment  with  3%  hydrochloric  acid,  without  dissolving  the  starch,  removes 
effectively  the  lime,  which  otherwise  would  be  precipitated  as  tartrate  by  the 
alkaline  copper  solution. 

19  Modified  McGlll  Method.— Tentative. 

Digest  1  gram  of  the  powder  with  150  cc.  of  3%  hydrochloric  acid  for  24  hours 
at  room  temperature,  with  occasional  shaking.  Filter  on  a  Gooch  crucible,  wash 
thoroughly  with  cold  water  and  then  once  each,  with  alcohol  and  ether.  Dry  at 
110°C.  (4  hours  is  usually  sufficient),  cool  and  weigh.  Burn  off  the  starch,  weigh 
again  and  determine  the  starch  by  difference. 

The  results  by  this  method  on  cream  of  tartar  powders  and  tartaric  acid  pow- 
ders agree  closely  with  those  obtained  by  copper  reduction.  On  phosphate,  alum 
and  alum-phosphate  powders  the  results  are  usually  satisfactory,  but  in  some 
instances  they  may  be  over  2%  too  high. 

ALUM  IN  THE  PRESENCE  OF  PHOSPHATES*. 

20  Qualitative  Test. — Tentative. 

(a)  In  baking  powder. — Burn  about  2  grams  of  the  sample  to  an  ash  in  a  porce- 
lain dish.  Extract  with  boiling  water  and  filter.  Add  to  the  filtrate  a  few  drops 
of  ammonium  chlorid  solution.     A  flocculent  precipitate  indicates  alum. 

(b)  In  cream  of  tartar. — Mix  about  1  gram  of  the  sample  with  an  equal  quantity 
of  sodium  carbonate,  burn  to  an  ash  and  proceed  as  in  (a). 

ASHi". 

21  INSOLUBLE  ASH  AND  PREPARATION  OF  SOLUTION.-TENTATIVE. 

Char  5  grams  of  the  sample  in  a  platinum  dish  at  a  heat  below  redjxess.  Boil  the 
carbonaceous  mass  with  dilute  hydrochloric  acid,  filter  into  a  500  cc.  graduated 
flask  and  wash  with  hot  water.  Return  the  residue,  together  with  the  paper,  to 
the  platinum  dish  and  burn  to  a  white  ash.  Boil  again  with  hydrochloric  acid, 
filter,  wash,  unite  the  2  filtrates  and  dilute  to  500  cc. 

Incinerate  the  residue  after  the  last  filtration  and  determine  the  ash  insoluble 
in  acid. 

22  IRON  AND  ALUMINIUM.-TENTATIVE. 

Draw  a  100  cc.  aliquot  of  the  solution,  prepared  as  directed  in  21,  and  separate 
silica,  if  necessary.  Mix  the  solution  with  sodium  phosphate  solution  in  excess. 
Add  ammonium  hydroxid  until  a  permanent  precipitate  is  obtained,  then  hydro- 
chloric acid,  drop  by  drop,  until  the  precipitate  is  dissolved.  Heat  the  solution 
to  about  50°C.,  mix  with  a  considerable  excess  of  50%  ammonium  acetate  solution 
and  4  cc.  of  80%  acetic  acid. 

As  soon  as  the  precipitate  of  aluminium  phosphate,  mixed  with  iron  phosphate, 
has  settled,  collect  on  a  filter,  wash  with  hot  water,  ignite  and  weigh. 

Fuse  the  mixed  phosphates  with  10  parts  of  sodium  carbonate,  dissolve  in  dilute 
sulphuric  acid,  reduce  with  zinc,  and  determine  the  iron  by  titration  with  a  standard 
permanganate  solution.  In  the  same  solution  determine  the  phosphoric  acid,  as 
directed  under  I,  6  or  9.  To  obtain  the  weight  of  alumina  (AI2O3)  subtract  the 
smn  of  the  weights  of  ferric  oxid  (Fe203)  and  phosphorus  pentoxid  (P2O6)  from  the 
weight  of  the  mixed  phosphates. 


346  METHODS   OF   ANALYSIS  [Chap. 

23  CALCroM.-TENTATIVE. 

Heat  the  combined  filtrate  and  washings,  obtained  in  22,  to  50°C.  and  add  an 
excess  of  ammonium  oxalate  solution.  Allow  to  stand  in  a  warm  place  until  the 
precipitate  has  settled,  filter,  wash  the  precipitate  with  hot  water,  dry,  ignite  over 
a  Bunsen  burner  and  finally  over  a  blast  lamp.  Cool  in  a  desiccator  and  weigh  as 
calcium  oxid. 

24  POTASSIUM  AND  SODIUM.— TENTATIVE. 

Evaporate  an  aliquot  of  the  solution,  prepared  as  directed  under  21,  nearly 
to  dryness  to  remove  the  excess  of  hydrochloric  acid,  dilute  and  heat  to  boiling. 
While  still  boiling  add  barium  chlorid  solution  so  long  as  a  precipitate  forms  and 
then  enough  barium  hydroxid  solution  to  make  the  liquid  strongly  alkaline.  As 
soon  as  the  precipitate  has  settled,  filter  and  wash  with  hot  water,  heat  the  filtrate 
to  boiling,  add  sufficient  ammonium  carbonate  solution  (1  part  of  ammonium  car- 
bonate in  5  of  2%  ammonium  hydroxid  solution)  to  precipitate  all  the  barium, 
filter  and  wash  with  hot  water.  Evaporate  the  filtrate  to  dryness  and  ignite  the 
residue  below  redness  to  remove  ammonium  salts.  Add  to  the  residue  a  little 
water  and  a  few  drops  of  ammonium  carbonate  solution.  Filter  into  a  tared  plat- 
inum dish,  evaporate,  ignite  below  redness  and  weigh  the  mixed  potassium  and 
sodium  chlorids. 

Determine  potassium  in  the  mixed  chlorids  as  directed  in  I,  45,  beginning  with 
"Digest  the  residue  with  hot  water,  filter  through  a  small  filter".  Calculate  the 
potassium  so  found  to  its  equivalent  of  potassium  chlorid  and  subtract  this  from 
the  weight  of  the  mixed  chlorids  to  obtain  the  weight  of  sodium  chlorid. 

25  PHOSPHORIC  ACID.-OFFICIAL. 

Mix  5  grams  of  the  sample  with  a  little  magnesium  nitrate  solution,  dry,  ignite, 
dissolve  in  dilute  hydrochloric  acid  and  dilute  the  solution  to  a  definite  volume. 
In  an  aliquot  of  the  solution  determine  phosphoric  acid  as  directed  under  I,  6  or  9. 

26  SULPHURIC  ACID^i.-TENTATIVE. 

Boil  5  grams  of  the  sample  gently  for  1^  hours  with  a  mixture  of  300  cc.  of  water 
and  15  cc.  of  concentrated  hydrochloric  acid.  Dilute  to  500  cc,  draw  off  a  100  cc. 
aliquot,  dilute  considerably,  precipitate  with  10%  barium  chlorid  solution,  filter 
the  precipitated  barium  sulphate  on  a  Gooch,  wash  with  hot  water,  dry,  ignite  and 
weigh. 

27  AMMONIA.-TENTATIVE. 

Introduce  2  grams  of  the  sample  into  a  distillation  flask,  add  300-400  cc.  of  water 
and  an  excess  of  sodium  hydroxid  solution,  connect  with  a  condenser  and  distil  into 
a  measured  amount  of  standard  acid.  Titrate  the  excess  of  acid  in  the  distillate 
with  standard  alkali,  using  methyl  red  or  cochineal  as  an  indicator. 

Ammonia  alum  is  often  an  ingredient  of  cream  of  tartar  substitutes  and  baking 
powders,  and  ammonium  carbonate  is-  occasionally  present  in  baking  powders. 

LEAD. 

Method  I.     Colorimetric  Method^^. — Tentative. 

(Applicable  in  the  absence  of  alum  and  phosphates.     Approximate  method  for 

preliminary  work.) 

28  REAGENTS. 

(a)  Sodium  bisulphite  solution. — Dissolve  10  grams  of  anhydrous  sodium  car- 
bonate in  sufficient  water  to  make  100  cc.  and  pass  sulphur  dioxid  into  the  solution 


XXVni]  BAKING    POWDERS  347 

until  carbon  dioxid  is  no  longer  evolved.  Dilute  a  little  of  this  solution  with  10 
volumes  of  water  as  needed  in  the  determination. 

(b)  10%  -potassium  cyanid  solution. 

(C)  Standard  lead  solution. — Dissolve  1.6  grams  of  crystallized  lead  nitrate,  pre- 
viously dried  over  sulphuric  acid,  in  a  liter  of  water  containing  a  few  drops  of  dilute 
nitric  acid.  One  cc.  of  this  solution  is  equivalent  to  1  mg.  of  metallic  lead.  Dilute 
1  cc.  of  this  solution  to  100  cc.  immediately  before  use  in  making  up  the  color 
standards. 

(d)  Lead-free  tartrate  solution. — Dissolve  200  grams  of  tartaric  acid  in  about  500 
cc.  of  hot  water,  cool,  add  40  cc.  of  the  sodium  bisulphite  solution,  heat  to  incipient 
boiling  and  test  a  few  drops  of  the  solution  with  potassium  sulphocyanate  solution 
to  ascertain  if  all  the  iron  is  reduced  to  the  ferrous  state,  repeating  the  treatment 
with  about  10  cc.  of  the  sodium  bisulphite  solution  in  case  ferric  iron  is  still  present. 
Cool,  add  20  cc.  of  the  10%  potassium  cyanid  solution,  and  then  strong  ammonium 
hydroxid  solution  until  the  solution  is  distinctly  alkaline  to  litmus  paper.  Boil 
until  the  solution  is  clear,  cool,  add  2  cc.  of  freshly  prepared,  colorless  ammonium 
sulphid  solution,  dilute  to  1  liter  and  allow  to  stand  overnight.  Filter  to  remove 
the  precipitated  sulphids,  boil  the  filtrate  until  hydrogen  sulphid  is  removed,  cool 
and  dilute  to  1  liter  with  water. 


PREPARATION   OF  SOLUTION. 


29 

(a)  Baking  powder. — Weigh  20  grams  of  the  sample  into  a  250  cc.  casserole,  add 
water  a  little  at  a  time  with  stirring  until  foaming  ceases,  then  hydrochloric  acid 
(1  to  1)  a  little  at  a  time  until  all  the  carbonate  is  decomposed  and  finally  5  cc. 
excess  of  the  hydrochloric  acid.  Cover  with  a  watch  glass  and  digest  on  a  steam 
bath  until  all  the  starch  is  hydrolyzed  as  shown  by  testing  1  or  2  drops  of  the  mix- 
ture with  iodin.  Filter  through  a  folded  filter  and  wash  the  filter  several  times  with 
small  portions  of  hot  water.  Treat  the  residue  on  the  filter  with  several  small  por- 
tions of  hot  nitric  acid  (sp.  gr.  1.2),  collect  the  acid  solution  in  a  separate,  small 
porcelain  dish,  evaporate  this  solution  to  dryness  on  a  water  bath  and  expel  nitric 
acid  by  several  treatments  and  evaporations  with  a  few  drops  of  concentrated 
hydrochloric  acid.  Rinse  the  contents  of  the  dish  through  a  small  filter  into  the 
main  solution  and  make  up  to  100  cc. 

(b)  Tartaric  acid  and  cream  of  tartar. — Dissolve  100  grams  of  the  sample  in  hot 
water,  add  50  cc.  of  hydrochloric  acid  (1  to  1),  filter  into  a  liter  graduated  flask, 
wash  the  filter  several  times  with  water,  and  then  treat  the  residue  on  the  filter 
with  several  small  portions  of  hot  nitric  acid  (sp.  gr.  1.2),  collect  the  acid  solution 
in  a  separate,  small  porcelain  dish,  evaporate  this  solution  to  dryness  on  a  water 
bath  and  expel  nitric  acid  by  several  treatments  and  evaporations  with  a  few  drops 
of  concentrated  hydrochloric  acid.  Rinse  the  contents  of  the  dish  through  a 
small  filter  into  the  main  solution,  finally  diluting  the  combined  filtrates  and  wash- 
ings to  a  liter. 

30  DETERMINATION. 

Introduce  50  cc.  of  the  solution,  prepared  as  directed  in  29,  into  a  beaker,  add 
2  cc.  of  the  sodium  bisulphite  solution,  heat  to  incipient  boiling,  and  test  a  few 
drops  of  the  solution  with  potassium  sulphocyanate  to  determine  if  all  the  iron  is 
reduced  to  the  ferrous  state,  repeating  the  treatment  with  the  sodium  bisulphite 
solution  if  ferric  iron  is  still  present.  Cool,  add  1  cc.  of  the  10%  potassium  cyanid 
solution  and  neutralize  to  litmus  with  strong  ammonium  hydroxid  solution;  finally 
add  an  excess  of  1  cc.  of.  the  last  reagent.    Boil  gently  until  clear  and  colorless,  cool 


348  METHODS   OF   ANALYSIS  [Chap. 

and  make  up  to  100  cc.  Treat  with  2  drops  of  freshly  prepared,  colorless  ammo- 
nium sulphid  solution,  mix  and  compare  in  a  colorimeter  with  standard  solutions, 
prepared  by  adding  measured  amounts  of  the  standard  lead  solution  to  50  cc.  of 
the  lead-free  tartrate  solution,  diluting  to  100  cc.  and  treating  with  2  drops  of 
freshly  prepared  colorless  ammoniima  sulphid  solution. 

The  final  comparison  should  be  made  with  a  standard  containing  approximately 
the  same  amount  of  lead,  and  the  addition  of  ammonium  sulphid  solution  should  be 
made  to  the  standards  and  the  solution  of  the  sample  at  the  same  time,  as  the  colors 
change  on  standing. 

31  Method  II. — Tentative. 

(Applicable  to  alum  or  phosphate  baking  powders  or  their  ingredients.) 

Weigh  100  grams  of  the  sample  into  a  1..3  liter  beaker  and  add  an  excess  of  hy- 
drochloric acid  (1  to  3)  in  small  portions,  keeping  down  excessive  frothing  with  a 
little  ether.  Heat  the  mixture  on  a  steam  bath  until  the  starch  is  hydrolyzed  and 
the  solution  is  quite  limpid.  Cool  and  add  200  cc.  of  50%  lead-free  ammonium 
citrate  solution.  Place  the  beaker  in  a  bath  of  cold  water  and  add  carefully  ammo- 
nium hydroxid  solution,  in  small  portions  with  constant  stirring,  until  the  mixture 
is  alkaline.  If  a  precipitate  forms,  add  sufficient  ammonium  citrate  solution  to 
dissolve  it.  Then  add  15  cc.  of  saturated  mercuric  chlorid  solution,  dilute  the 
mixture  to  about  1200  cc,  saturate  with  hydrogen  sulphid  and  allow  to  stand 
until  the  precipitate  has  settled  (15-20  minutes).  Filter  and  wash  the  precipitate 
with  hydrogen  sulphid  water.  Place  the  paper  and  precipitate  in  a  small  casserole, 
add  10  cc.  of  concentrated  nitric  acid  and  2  cc.  of  concentrated  sulphuric  acid  and 
heat  on  a  hot  plate  until  the  mixed  acids  have  been  slowly  driven  off.  Heat  the 
residue  in  a  muffle  at  low  redness  until  the  mercury  salts  have  volatilized.  Cool 
the  casserole  and  leach  the  residue  several  times  with  25%  ammonium  acetate  solu- 
tion, made  slightly  alkaline  with  ammonium  hydroxid,  pass  the  teachings  through 
a  small  filter  into  a  beaker  and  finally  wash  the  residue  and  filter  paper  with  a 
little  hot  water.  Acidify  the  combined  filtrate  and  washings  with  acetic  acid,  add 
an  excess  of  potassium  dichromate  solution  and  allow  to  stand  overnight.  Filter 
on  a  tared  Gooch,  wash  with  water,  dry  for  30  minutes  at  125°-150°C.,  cool  and 
weigh  as  lead  chromate.  Calculate  the  weight  of  metallic  lead.  Conduct  a  blank 
determination  upon  all  the  reagents  and  correct  the  result  accordingly. 

32  Method  III.— Tentative. 

(Applicable  to  alum  or  phosphate  baking  powders  or  their  ingredients.) 

Transfer  200  grams  of  the  sample  to  a  3  liter  Jena  flask,  add  300  cc.  of  concen- 
trated nitric  acid  in  small  portions,  shake  thoroughly  after  each  addition  and 
heat  the  mixture  slowly,  shaking  repeatedly.  When  brown  fumes  begin  to  appear 
at  the  mouth  of  the  flask,  discontinue  heating  and  insert  a  stemless  funnel  in  the 
neck  of  the  flask.  As  soon  as  the  action  has  moderated,  place  the  flask  on  an 
asbestos  gauze  over  a  small  Bunsen  flame.  When  the  action  becomes  weak,  add 
slowly  90  cc.  of  concentrated  sulphuric  acid  and  continue  heating  until  the  fumes 
disappear.  Then  add  25  cc.  of  concentrated  nitric  acid  from  time  to  time  with  con- 
tinued heating  until  all  the  starch  is  completely  oxidized.  Usually  3-4  additions 
of  25  cc.  portions  of  nitric  acid  suffice.  Finally  expel  the  nitric  acid  as  completely 
as  possible.  Cool,  add  400  cc.  of  water,  shake  and  allow  to  settle.  The  soluble  sul- 
phates of  sodium,  potassium,  aluminium,  iron,  etc.,  go  into  solution,  while  calcium 
sulphate  and  most  of  the  lead  sulphate  will  be  precipitated.     Filter  through  an  18 


XXVni]  BAKING    POWDERS  349 

cm.  folded  filter  into  a  liter  Erlenmeyer  flask,  rinse  the  3  liter  flask  2-3  times  with 
small  portions  of  water  and  pour  the  rinsings  through  the  filter.  Reserve  the  fil- 
trate for  the  recovery  of  dissolved  lead  salts.  Open  the  filter,  containing  the  pre- 
cipitate, over  a  600  cc.  beaker  and  wash  the  precipitate  into  it.  Then  transfer  the 
contents  of  the  beaker  to  a  2  liter  Erlenmeyer  flask  together  with  whatever  pre- 
cipitate remains  in  the  3  liter  flask.  Dilute  the  contents  of  the  flask  so  as  to  nearly 
fill  the  latter,  stir  thoroughly  to  dissolve  the  calcium  sulphate,  add  20  cc.  of  strong 
acetic  acid  and  saturate  the  liquid  thoroughly  with  hydrogen  sulphid.  Stopper 
the  flask  and  set  aside  until  the  precipitate  settles.  Siphon  off  the  supernatant 
liquid.  When  much  calcium  sulphate  is  present,  one  such  treatment  is  not  suffi- 
cient to  dissolve  all  of  it.  In  this  case  refill  the  flask  with  water,  again  acidify, 
saturate  with  hydrogen  sulphid  and  allow  to  stand  till  the  calcium  sulphate  is 
practically  all  dissolved  and  the  residue  of  sulphids  is  dark  colored.  Solution  may 
be  hastened  by  the  addition  of  lead-free  sodium  acetate  to  the  water  (50-75  grams 
to  each  2  liters). 

Treat  the  liquid  containing  the  soluble  sulphates  separately  to  recover  the  trace 
of  lead  which  it  may  contain.  Partially  neutralize  with  ammonium  hydroxid  solu- 
tion just  short  of  the  point  of  producing  a  permanent  precipitate  of  aluminium 
phosphate,  saturate  with  hydrogen  sulphid  and  allow  the  precipitate  to  settle. 
Some  iron  sulphid  also  will  usually  be  precipitated.  The  sulphid  precipitations 
should  be  made  in  very  slightly  acid  solutions,  otherwise  lead  sulphid  will  not  be 
precipitated  completely.  Siphon  off  the  supernatant  liquid,  transfer  the  precipi- 
tate to  an  11  cm.  filter  and  wash  with  hydrogen  sulphid  water.  Transfer  the  first 
precipitate  remaining  in  the  2  liter  flask  to  a  second  11  cm.  filter  and  treat  in  the 
same  way.  Place  the  2  filters  with  their  contents  in  a  200  cc.  Erlenmeyer  flask, 
add  10  cc.  of  concentrated  nitric  acid  and  5  cc.  of  concentrated  sulphuric  acid, 
insert  a  stemless  funnel  in  the  neck  and  heat  to  completely  oxidize  the  material. 
When  the  nitric  acid  has  all  been  expelled  and  the  residue  darkens,  add  more  nitric 
acid  until  no  such  darkening  occurs.  Finally  heat  the  residue  till  fumes  of  sulphur 
trioxid  are  given  off,  cool  and  add  15  cc.  of  water.  Filter  through  a  7  cm.  filter, 
rinse,  then  wash  the  filter  twice  with  small  portions  of  dilute  sulphuric  acid  and 
finally  with  a  little  water.  Place  a  clean  150  cc.  beaker  under  the  filter,  dissolve 
the  precipitate  in  15-25  cc.  of  ammonium  acetate  solution  [1  part  of  99%  acetic 
acid,  1  of  water  and  1  of  ammonium  hydroxid  (sp.  gr.  0.90);  made  neutral  to  lit- 
mus paper]  and  wash  thoroughly  with  water. 

Acidify  the  filtrate  and  washings  with  acetic  acid,  add  an  excess  of  potassium 
dichromate  solution,  heat  on  a  steam  bath  and  allow  to  cool  and  settle.  Filter  on 
a  tared  Gooch  prepared  with  a  thick  layer  of  asbestos  which  has  been  previously 
dried  at  125°C.,  wash  with  water,  dry  at  about  125°C.  and  weigh  as  lead  chromate. 

33  Method  IV.— Tentative. 

(Applicable  in  the  absence  of  alum  and  phosphates.) 

Weigh  100  grams  of  the  sample  into  a  liter  beaker  and  add  an  excess  of  hydro- 
chloric acid  (1  to  3)  in  small  portions,  keeping  down  excessive  frothing  with  a  little 
ether.  Heat  the  mixture  on  a  steam  bath  until  the  starch  is  hydrolj'zed  and  the 
solution  is  quite  limpid.  Cool,  add  ammonium  hj'droxid  solution  until  distinctly 
alkaline,  dilute  to  about  800-900  cc.  and  saturate  with  hydrogen  sulphid.  Allow 
the  mixture  to  stand  for  3-4  hours  or  until  the  precipitate  has  settled,  filter  on  a 
12.5  cm.  close-textured  paper  and  wash  the  precipitate  several  times  with  hydrogen 
sulphid  water.  Place  the  filter  paper  and  precipitate  in  a  100  cc.  Erlenmeyer  flask, 
add  5  cc.  of  concentrated  sulphuric  acid  and  5  cc.  of  concentrated  nitric  acid  and 


METHODS    OF  ANALYSIS 

heat  on  a  hot  plate,  with  occasional  additions  of  small  portions  of  concentrated 
nitric  acid,  until  the  mixture  no  longer  blackens  when  evaporated  to  the  point  at 
which  white  fumes  of  sulphur  trioxid  appear.  Cool,  dilute  with  20  cc.  of  water, 
warm  until  the  ferric  sulphate  goes  into  solution,  cool  and  then  add  40  cc.  of  95% 
alcohol  by  volume.  Allow  to  stand  overnight,  filter  on  a  Gooch  and  wash  with 
95%  alcohol.  Dissolve  the  lead  sulphate  remaining  on  the  filter  by  washing  with 
20  cc.  of  25%  ammonium  acetate  solution,  rendered  slightly  alkaline  with  ammo- 
nium hydroxid,  collect  the  filtrate  in  a  small  beaker,  passing  it  through  the  filter 
3^  times.  Finally  wash  the  filter  with  hot  water,  acidify  the  combined  filtrate 
and  washings  with  acetic  acid,  add  an  excess  of  potassium  dichromate  solution  and 
allow  to  stand  overnight.  Filter  on  a  small,  tared  Gooch,  wash,  dry  for  30  minutes 
at  125°-150°C.  and  weigh  as  lead  chromate.     Calculate  the  metallic  lead. 

34  ARSENIC— TENTATIVE. 

Introduce  5  grams  of  the  sample  directly  into  the  generator  described  under 
XII,  2  (Fig.  7),  add  10  cc.  of  water,  a  little  at  a  time  to  prevent  foaming  over, 
and  then  15  cc.  of  concentrated,  arsenic-free  hydrochloric  acid,  introducing  it  drop 
by  drop  until  foaming  ceases.  Heat  on  a  steam  bath  until  a  drop  of  the  mixture, 
when  diluted  and  treated  with  iodin  solution,  shows  no  blue  color.  Then  dilute  to 
about  30  cc.  with  water,  add  4  cc.  of  potassium  iodid  solution  and  continue  from 
this  point  as  directed  under  XII,  4,  beginning  with  "Heat  to  about  90°C.",  except 
that  the  blank  and  the  standards  for  comparison  are  made  by  the  use  of  the  arsenic- 
free  hydrochloric  acid  of  the  same  concentration  as  that  used  in  the  determination. 

BIBLIOGRAPHY. 

1  J.  Am.  Chem.  Soc,  1899,  21:  396. 

2  Ibid.,  1896,  18:1. 

3  Conn.  Agr.  Exp.  Sta.  Kept.,  1900,  (11),  p.  169. 

*  Inland  Revenue  Dept.,  Canada,  Bull.  68,  p.  31. 

'"  Catlin.  Baking  Powders:  A  Treatise  on  Their  Character,  Method  for  Deter- 
mination of  Their  Values,  etc.  p.  20. 

6  Ann.  chim.  anal.,  1899,  4:  263. 

7  Conn.  Agr.  Exp.  Sta.  Rept.,  1900,  (11),  p.  180. 

8  Ibid.,  p.  174. 

5  Rept.  Mass.  State  Board  of  Health,  1899,  p.  638. 
1"  Conn.  Agr.  Exp.  Sta.  Rept.,  1900,  (II),  p.  178. 

11  U.  S.  Bur.  Chem.  Bull.  13  (V),  p.  596;  Conn.  Agr.  Exp.  Sta.  Rept.,  1900,  (II), 
p.  179. 

12  J.  Assoc.  Official  Agr.  Chemists,  1915,  1:  249. 


XXIX.     DRUGS. 

Caffein  and  Acetanilid  in  Mixtures. 

1  preparation  of  sample  and  solution.— tentative. 

(a)  If  the  sample  is  already  in  powder  form,  rub  thoroughly  in  a  mortar  and 
keep  in  a  tightly  corked  tube  or  flask.  Powders  in  paper,  cachet  or  capsule  con- 
tainers are  frequently  of  such  fineness  as  to  require  little  further  trituration  except 
to  produce  a  uniform  product.  On  a  tared  5.5  cm.  filter  weigh  0.3-0.5  gram  of  the 
sample  or,  if  preferred,  an  amount  equal  to,  or  a  multiple  of,  the  average  unit  dose 
(previously  ascertained  by  weighing  collectively  20  or  more  such  doses),  wash  wath 
successive  5-10  cc.  portions  of  the  chloroform  (30-50  cc.  are  usually  sufficient)  until 
the  extraction  is  complete  as  indicated  by  the  absence  of  any  residue  after  evapora- 
tion of  a  small  portion  of  the  last  washing.  Collect  the  solution  in  a  200  cc.  Erlen- 
meyer  flask,  connect  the  flask  with  a  condenser  by  means  of  a  cylindrical  Kjeldahl 
connecting  bulb^  and  distil  until  the  volume  is  reduced  to  about  10  cc. 

(b)  If  the  caffein  is  present  in  the  citrated  form,  or  the  composition  of  the  mix- 
ture precludes  complete  extraction  as  directed  in  (a),  weigh  out  the  desired  amount, 
transfer  to  a  Squibb  separatory  funnel,  add  50  cc.  of  the  chloroform  and  20  cc.  of 
water,  shake  vigorously  and,  after  clearing,  draw  off  the  lower  layer  through  a 
small,  dry  filter  into  a  200  cc.  Erlenmeyer  flask.  In  the  case  of  coated  tablets  and 
pills,  ascertain  their  average  weight,  powder  in  a  mortar  and  weigh  out  for  each 
determination  an  amount  equivalent  to  one  or  more  tablets  or  pills.  Repeat  the 
extraction  twice,  using  50  cc.  portions  of  the  chloroform  for  each  extraction.  Dis- 
til the  combined  chloroform  extracts  to  about  10  cc. 

(C)  In  the  case  of  dilute  alcoholic  solutions,  evaporate  a  measured  quantity  on 
a  steam  bath  until  most  of  the  alcohol  has  been  expelled,  or  take  an  aliquot  of 
the  residue  from  an  alcohol  determination;  transfer  to  a  separatory  funnel  by  pour- 
ing and  rinsing  with  a  minimum  of  water  so  that  the  final  volume  does  not  greatly 
exceed  20  cc,  and  then,  in  order  to  avoid  any  loss  of  acetanilid  by  hydrolysis  during 
evaporation,  add  a  little  solid  sodium  bicarbonate  and  a  drop  of  acetic  anhydrid. 
(Should  the  preparation  contain  alkaloids,  acidify  with  a  few  drops  of  dilute  sul- 
phuric acid  immediatelj'  after  acetylization  to  retain  such  basic  material  in  solu- 
tion.) Add  50  cc.  of  the  chloroform,  shake  vigorously  and,  after  clearing,  draw  off 
the  chloroform  layer  through  a  filter  into  a  200  cc.  Erlenmeyer  flask.  Repeat  the 
extraction  twice,  using  50  cc.  portions  of  the  chloroform  for  each  extraction,  and 
distil  the  combined  chloroform  washings  to  a  volume  of  about  10  cc. 

CAFFEIN  AND  ACETANILID.— TENTATIVE. 

2  REAGENTS. 

(a)  Standard  hromid-hromate  solution. — Dissolve  50  grams  of  potassium  hydroxid 
in  a  small  quantity  of  water,  add  a  slight  excess  of  bromin,  dilute  with  water  to  dis- 
solve any  separated  salts,  boil  to  expel  excess  of  bromin  and  dilute  to  1  liter.  Stand- 
ardize the  solution  against  recrystallized  acetanilid  and  adjust  the  solution  so  that 
1  cc.  is  equivalent  to  5  or  10  mg.  of  acetanilid  as  desired. 

(b)  C/iZoro/or??}.— Redistilled  and  residue-free.  All  corks  used  in  the  distillation 
should  be  treated  previously  with  chloroform. 

351 


352  METHODS    OP   ANALYSIS  [Chap. 

(C)  Wagner's  reagent. — Dissolve  2  grams  of  iodin  and  6  of  potassium  iodid  in  a 
minimum  amount  of  water  and  dilute  to  100  cc. 

3  CAFFEIN.— TENTATIVE. 

Treat  the  chloroform  extract,  obtained  inl,  with  10  cc.  of  sulphuric  acid  (1  to 
10)  and  digest  on  a  steam  bath  until  the  contents  of  the  flask  are  reduced  to  5  cc. 
Add  10  cc.  of  water  and  continue  the  digestion  until  the  liquid  is  again  reduced  to 
5  cc,  then  cool  and  transfer  to  a  separatory  funnel  with  a  minimum  of  water,  so 
that  the  final  volume  does  not  greatly  exceed  20  cc.  Add  50  cc.  of  the  chloroform, 
extract  in  the  usual  way  and,  after  clearing,  withdraw  the  lower  layer  through  a 
small,  dry  filter  into  a  200  cc.  Erlenmeyer  flask.  Repeat  the  extraction  with  two 
50  cc.  portions  of  the  chloroform.  On  the  completion  of  the  third  extraction, 
distil  the  combined  extracts  down  to  about  10  cc,  finally  transferring  the  residual 
liquid,  bj^  washing  with  chloroform,  to  a  tared  beaker  or  crystallizing  dish.  Allow 
the  solution  to  evaporate  spontaneously,  or  by  gentle  heat  and  an  air  blast,  to 
apparent  dryness.     Cool  and  allow  to  stand  until  the  weight  becomes  constant. 

Chloroform  extracts  in  addition  to  caffein  and  acetanilid  certain  oils,  fats,  waxes, 
resins,  pigments  and  other  substances  from  those  preparations  which  contain  pow- 
dered cinnamon,  celery  seed,  ginger  or  other  vegetable  products.  These  appear  either 
in  suspension  or  solution  after  the  caffein-acetanilid  mixture  has  been  digested  and 
contaminate  the  caffein.  Remove  any  suspended  impurities  by  filtering  through 
a  small,  moistened  filter  immediately  after  hydrolysis  and  prior  to  extraction  with 
chloroform.  Should  the  recovered  caffein  be  deeply  colored  or  contaminated  with 
foreign  matter,  purify  it  as  follows:  Dissolve  in  very  dilute  sulphuric  acid  (about 
5  cc  of  N/5  acid  for  every  100  mg.  of  caffein),  filter,  if  necessary,  through  a  mois- 
tened filter,  add  15-20  cc.  of  Wagner's  reagent,  sufficient  at  least  to  distinctly  color 
the  supernatant  liquid,  stir  and  allow  to  stand  an  hour,  preferably  in  a  refrigerator. 
Filter  and  wash  the  periodid  with  a  few  cc.  of  iodin  solution,  transfer  both  filter  and 
precipitate  to  a  separatory  funnel,  using  not  more  than  20  cc.  of  water,  decolorize 
with  a  crystal  of  sodium  thiosulphate,  then  extract  with  three  50  cc.  portions  of 
chloroform  and  proceed  as  directed  above. 

4  ACETANILID.— TENTATIVE. 

Transfer  the  solution  of  anilin  sulphate,  remaining  in  the  separatory  funnel 
in  3,  to  the  Erlenmeyer  flask  used  in  effecting  hydrolysis,  then  heat  10  minutes  on 
a  steam  bath  to  expel  all  traces  of  chloroform.  Wash  the  filter,  used  in  the  pre- 
ceding operation  to  dry  the  chloroform  solution  of  caffein,  with  5  cc.  of  water, 
adding  the  latter  to  the  main  solution  of  anilin  sulphate.  Add  10  cc.  of  concen- 
trated hydrochloric  acid,  then  run  in  the  standard  bromid-bromate  solution  until 
a  faint  yellow  coloration  remains,  rotating  the  flask  sufficiently  to  agglomerate  the 
precipitated  tribromanilin.  Calculate  the  quantity  of  acetanilid  from  the  number 
of  cc.  required  to  complete  the  precipitation. 

Caffein  and  acetanilid  are  the  2  principal  ingredients  of  the  preparation  known 
as  "acetanilid  compound",  a  further  constituent  being  sodium  bicarbonate.  The 
latter  appears  as  the  chloroform-insoluble  residue  and  may  be  determined  by  ti- 
trating such  residue,  or  one  obtained  by  titrating  a  portion  of  the  original  mixture, 
with  standard  acid,  using  congo  red  as  an  indicator.  The  bicarbonate  may  also 
be  determined  by  igniting  the  original  sample,  or  the  chloroform-insoluble  residue, 
with  sulphuric  acid  and  weighing  the  resulting  sodium  sulphate. 

Should  the  "acetanilid  compound"  be  combined  with  sodium  bromid,  the  latter, 
in  the  absence  of  other  halides,  may  be  determined  volumetrically  by  the  Volhard 
method  [III,  15]. 


XXIX]  DRUGS  353 

CAFFEIN  and  ACETPHENETIDIN  fPHENACETIN)  IN  MIXTURES. 

5  PREPARATION  OF  SAMPLE  AND  SOLUTION.-TENTATIVE. 

In  the  case  of  preparations  containing  acetphenctidin  instead  of  acetanilid,  but 
otherwise  identical,  make  the  gross  separation  of  the  caffein-acetphenetidin  mix- 
ture as  directed  under  1 . 

6  CAFFEIN.-TENTATIVE. 

Treat  the  chloroform  extract,  obtained  as  directed  under  1,  with  10  cc.  of  sul- 
phuric acid  (1  to  10)  and  digest  on  a  steam  bath  until  the  liquid  is  reduced  to  about 
5  cc.  Dilute  with  10  cc.  of  water  and  continue  the  digestion  until  the  volume  is 
again  reduced  to  5  cc,  then  add  10  cc.  of  water  and  continue  heating  until  the 
residual  liquid  amounts  to  8-10  cc.  If,  during  the  digestion,  particles  of  acet- 
phenctidin remain  on  the  sides  of  the  flask  rinse  them  into  the  solution  vnth  a  few 
drops  of  chloroform. 

Great  care  must  also  be  given  to  the  degree  of  evaporation.  Should  the  aqueous- 
acid  solution  and  suspension  of  caffein-acetphenetidin  be  concentrated  far  beyond 
the  limits  indicated,  more  or  less  phenetidin  sulphonate  is  likely  to  be  formed, 
which  later  resists  acetylization  and  conversion  to  acetphenctidin. 

Cool  and  transfer  with  water  to  a  separatory  funnel,  so  that  the  final  volume  does 
not  greatly  exceed  20  cc.     Then  proceed  as  directed  under  3. 

7  ACETPHENETIDIN.-TENTATIVE. 

Wash  the  filter,  used  to  dry  the  chloroform  in  6,  with  5  cc.  of  water,  receiving  the 
te  r  in  the  separatory  funnel  containing  the  solution  of  phenetidin  sulphate. 
Treat  with  successive  small  portions  of  solid  sodium  bicarbonate  until,  after  com- 
plete neutralization  of  free  acid,  an  excess  of  the  former  remains  at  the  bottom  of  the 
mixture.  Add  50  cc.  of  chloroform  and  for  every  0.10  gram  of  acetphenetidin,  known 
or  believed  to  have  been  present,  5  drops  of  acetic  anhydrid;  shake  vigorouslj',  allow 
to  clear,  then  withdraw  the  chloroform  into  a  second  separatory  funnel  containing 
5  cc.  of  water.  Shake  this  mixture  and,  after  clearing,  pass  the  solvent  through  a 
small,  dry  filter  into  a  200  cc.  Erlenmeyer  flask.  Distil  over  about  40  cc.  of  the 
chloroform,  make  up  the  distillate  to  50  cc.  with  chloroform,  add  this  to  the  mate- 
rial in  the  first  separatory  funnel  and  extract  again.  Withdraw  the  chloroform 
layer  to  the  second  separatory  funnel,  wash  and  distil  about  50  cc.(for  use  in  the 
final  extraction).  Distil  the  chloroform  down  to  about  10  cc,  transfer  with  sufficient 
fresh  solvent  to  a  tared  50  cc.  beaker  or  crystallizing  dish,  evaporate  on  the  steam 
bath  to  apparent  dryness,  finally  removing  any  considerable  e.xcess  of  acetic  anhy- 
drid by  repeated  additions  of  1  cc.  of  chloroform  and  a  drop  of  alcohol.  The  re- 
formed acetphenetidin  should  finalh*  appear  as  a  whitish,  crystalline  mass  with 
a  faint,  acetous  odor  which  disappears  completely  on  standing  some  hours  in  the 
open,  or  in  a  vacuum  desiccator  over  lime.  Weigh  from  time  to  time  until  the 
final  weight  differs  from  the  preceding  by  not  more  than  0.5  mg. 

CAFFEIN  AND  ANTIPYRIN  IN  MIXTURES'. 

8  PREPARATION  OF  SAMPLE  AND  SOLUTION.-TENTATIVE. 

(a)  Extract  a  weighed  portion  of  the  finely  powdered  sample  on  a  filter  with 
chloroform  to  separate  the  caffein  and  antipyrin  from  the  usual  excipients  of  tab- 
let and  pill  combinations.  Distil  off  the  greater  part  of  the  chloroform  and  evap- 
orate the  remainder  on  the  steam  bath. 


354  METHODS    OF  ANALYSIS  [Chap. 


(b)  In  the  case  of  alcoholic  preparations,  remove  the  alcohol  from  a  measured 
amount  of  the  sample  by  heating  on  a  steam  bath.  Extract  the  residue  with  three 
50  cc.  portions  of  chloroform  in  a  separatory  funnel.  Distil  off  the  greater  por- 
tion of  the  chloroform  and  evaporate  the  remainder  on  a  steam  bath. 

9  ANTIPYRIN.-TENTAXrVE. 

Transfer  the  residue,  obtained  in  8,  which  should  weigh  about  0.25  gram,  to  a 
150  cc.  separatory  funnel  by  means  of  two  5  cc.  portions  of  alcohol-free  chloroform, 
followed  by  10  cc.  of  water.  Add  1  gram  of  sodium  bicarbonate  and  10-15  cc.  of 
N/5  iodin  (or  double  the  quantity  of  N/10  iodin),  adding  the  latter  in  small  por- 
tions and  shaking  the  mixture  vigorously  after  each  addition.  The  iodin  should 
then  be  in  excess  of  that  required  to  convert  all  the  antipyrin  into  the  mono-iod 
derivative.  If  not,  add  a  little  more  and  shake  the  mixture  again.  Remove  the 
free  iodin  with  a  small  crystal  of  sodium  thiosulphate,  add  15  cc.  of  chloroform, 
shaking  vigorously  for  1  minute.  After  clearing,  draw  off  the  chloroform  solution 
into  a  second  separatory  funnel,  wash  with  5  cc.  of  water,  filter  through  a  small, 
dry  filter  into  a  tared  50  cc.  beaker  and  evaporate  to  apparent  dryness  on  the  steam 
bath,  using  an  air  blast.  Repeat  the  extraction  with  two  (three,  if  N/10  iodin  is 
used)  25  cc.  portions  of  chloroform,  wash,  filter  and  evaporate  each  portion  as 
above.  Dry  the  nearly  colorless,  crystalline  residue  of  caffein  and  iodantipyrin  30 
minutes  at  105°C.,  cool  and  weigh.     Designate  this  weight  as  "a". 

Dissolve  the  composite  residue  in  5  cc.  of  glacial  acetic  acid,  add  10  cc.  of 
saturated  sulphur  dioxid  solution,  then  transfer  with  hot  water  to  a  400-500 
cc.  beaker  until  the  final  volume  amounts  to  about  200  cc.  Add  sufficient  silver 
nitrate  solution  to  precipitate  all  the  iodin  (about  0.3  gram  of  silver  nitrate);  then 
a  few  drops  of  nitric  acid,  heat  nearly  to  boiling  and  stir  to  agglomerate  the  silver 
iodid.  Add  15  cc.  of  concentrated  nitric  acid,  cover  the  beaker  with  a  watch  glass 
and  boil  gently  for  5  minutes.  Filter  by  decantation  through  a  tared  Gooch,  wash 
the  precipitate  once  with  a  little  alcohol,  then  with  two  100  cc.  portions  of  boiling 
water  and  finally  transfer  the  iodid  to  the  crucible.  Wash  several  times  with  hot 
water  and  again  with  alcohol  to  remove  traces  of  organic  matter,  dry  30  minutes 
in  an  air  bath  at  110°C.,  cool  and  weigh.  The  weight  of  silver  iodid  multiplied  by 
0.8012  gives  the  weight  of  antipyrin. 

10  CAFFEIN.-TENTATIVE. 

Calculate  the  quantity  of  caffein  by  multiplying  the  weight  of  silver  iodid  by 
1.3374  and  subtracting  the  product  from  the  weight  "a"  above. 

In  the  analysis  of  a  mixture  containing  caffein,  antipyrin,  acetanilid  and  sodium 
salicylate,  the  following  steps  are  essential  in  effecting  a  separation:  (1)  Extraction 
of  caffein,  acetanilid  and  antipyrin  with  chloroform  from  the  aqueous  soda  solution; 
(2)  Hydrolysis  with  sulphuric  acid  of  the  3  substances  thus  separated  preliminary 
to  the  determination  of  caffein  and  antipyrin  as  directed  in  9  and  10. 

Acetanilid  and  Acetphenetidin  (Phenacetinj  in  Mixtures', 
acetphenetidin.— tentative. 

11  REAGENTS. 

(a)  Purified  iodin. — Dissolve  2  parts  of  resublimed  iodin  and  1  of  potassiimi  iodid 
in  1  of  water,  pour  the  clear  solution  into  a  large  volume  of  water,  filter  and  wash 
the  finely  precipitated  iodin  several  times  on  a  porous  plate  with  water.  Dry  in 
the  air  and  finally  in  a  desiccator  over  sulphuric  acid  where  it  is  kept  in  a  glass- 
stoppered  weighing  bottle. 


XXIX]  DRUGS  355 

(b)  Standard  sodium  thiosulphate  solution. — Dissolve  30  grams  of  crystallized 
sodium  thiosulphate  in  water  and  dilute  to  1  liter.  Standardize  this  solution  against 
the  purified  iodin  as  follows:  Weigh  out  about  0.3  gram  of  the  purified  iodin  in  a 
small,  glass  capsule  (about  §  inch  high  and  f  inch  diameter),  provided  with  a  closely 
fitting  glass  cap  or  stopper,  and  place  the  capsule  in  a  200  cc.  Erlenmeyer  flask  con- 
taining 0.5  gram  of  potassium  iodid  dissolved  in  10  cc.  of  water.  After  complete 
solution,  titrate  with  the  sodium  thiosulphate  solution,  using  1  or  2  drops  of  starch 
solution  as  an  indicator. 

(C)  Standard  iodin  solution. — Dissolve  40  grams  of  potassium  iodid  in  the  least 
possible  quantity  of  water,  add  30  grams  of  the  purified  iodin  and,  after  solution, 
dilute  to  1  liter.  Standardize  25  cc.  of  this  solution  against  the  standard  sodium 
thiosulphate  solution. 

12  DETERMINATIOxV. 

(1)  Place  0.2  gram  of  the  acetphenetidin-acetanilid  mixture  in  a  50  cc.  lipped 
Erlenme3-er  flask,  add  2  cc.  of  glacial  acetic  acid,  heat  gently  over  a  wire  gauze  to 
complete  solution  and  dilute  with  40  cc.  of  water,  previously  warmed  to  70°C. 
Transfer  the  clear  liquid  with  two  10  cc.  portions  of  warm  (40°C.)  water  to  a  glass- 
stoppered,  100  cc.  graduated  flask  containing  25  cc.  of  the  standard  iodin  solution 
warmed  to  40°C.  Stopper,  mix  thoroughly,  then  add  3  cc.  of  concentrated  hydro- 
chloric acid,  continue  shaking  until  crystallization  begins  and  then  set  aside  to 
cool.  If  the  ratio  of  acetphenetidin  to  acetanilid  is  equal  to  or  greater  than  unity, 
crystalline  scales  will  form  almost  immediately  on  the  addition  of  acid.  As  the 
proportion  of  acetanilid  increases,  however,  the  periodid  tends  to  remain  in  the  liquid 
state.  In  such  cases,  gentle  agitation  or  rotation  of  the  flask  in  water,  warmed 
not  to  exceed  40°C.,  hastens  the  formation  of  crystals.  When  the  contents  of  the 
flask  are  at  room  temperature,  fill  with  water  to  within  2-3  cc.  of  the  mark,  mix 
thoroughly  and  allow  to  stand  overnight.  Fill  to  the  mark  with  water,  mix  thor- 
oughly, allow  to  stand  30  minutes,  filter  through  a  5.5  cm.  dry,  closely  fitted  filter 
into  a  50  cc.  graduated  flask,  rejecting,  however,  about  15  cc.  of  the  first  runnings 
but  reserving  them  for  the  recovery  of  acetanilid.  Transfer  the  50  cc.  aliquot  to  a 
200  cc.  Erlenmeyer  flask  and  titrate  with  the  standard  sodium  thiosulphate  solution. 
Calculate  the  amount  of  acetphenetidin  from  the  following  formula: 

Acetphenetidin  =  I  (0.0896  X  N)  in  which 

0.0S96  =  the  quantity  of  acetphenetidin  contained  in  1  cc.  of  a  normal 
solution  of  this  substance; 
N  =  the  normality  of  the  standard  sodium  thiosulphate  solution 

employed;  and 
I  =  the  number  of  cc.  of  the  standard  sodium  thiosulphate  solu- 
tion corresponding  to  the  iodin  combined  with  the    acet- 
phenetidin. 

The  formula  of  the  precipitated  periodid,  which  constitutes  the  basis  for  the  above 
determination,  is  (C>H50.C6ll4XH.COCH3)2HI.l4. 

(2)  The  gravimetric  determination  of  acetphenetidin  may,  if  desired,  be  efi"ected 
as  follows:  Filter  off  the  periodid,  preferably  by  suction,  wash  with  10-15  cc.  of  the 
standard  iodin  solution,  then  transfer  together  with  the  filter  to  a  scparatory  funnel, 
using  not  over  50  cc.  of  water.  Remove  both  free  and  added  iodin  with  a  few  small 
crystals  of  sodium  sulphite  and  extract  the  liquid  with  three  50  cc.  portions  of 
chloroform,  washing  each  portion  subsequently  into  a  second  separatory  funnel  with 
5  cc.  of  water.     After  washing  and  clearing,  filter  the  chloroform  solution  through 


356  METHODS    OF   ANALYSIS  [Chap. 

a  dry  5.5  cm.  filter  into  a  200  cc.  Erlenmeyer  flask,  distil  off  most  of  the  chloro- 
form, transfer  the  residual  solution  (5-10  cc),  by  means  of  a  little  chloroform,  to 
a  small,  tared  beaker  or  crystallizing  dish,  evaporate  to  dryness  on  a  steam  bath, 
cool  and  weigh. 

For  the  identification  of  acetphenetidin,  either  alone  or  in  admixture  with  acet- 
anilid,  the  following  test  will  be  found  of  value':  To  1-2  mg.  of  the  sample  in  a  test 
tube  add  a  drop  of  acetic  acid,  0.5  cc.  of  water  and  1  cc.  of  N/10  iodin,  warm  the 
mixture  to  about  40°C.,  then  add  a  drop  of  concentrated  hydrochloric  acid.  If 
acetphenetidin  alone  is  present,  its  periodid  separates  almost  immediately  in  the 
form  of  reddish  brown  leaflets  or  needle-like  crystals.  If  the  sample  consists  largely 
of  acetanilid,  the  separation  takes  place  on  cooling  and  shaking  the  liquid.  In  the 
presence  of  considerable  acetanilid,  the  periodid  first  separates  as  minute,  oily 
globules,  which,  on  vigorous  shaking,  gradually  become  crystalline.  This  test  is  so 
delicate  that  as  little  as  0.5  mg.  of  acetphenetidin  may,  if  alone,  be  detected  in 
the  form  of  its  characteristic  periodid. 

13  ACETANILID.-TENTATIVE. 

(1)  If  the  combined  weight  of  the  acetphenetidin-acetanilid  mixture  is  known, 
determine  that  of  the  latter  ingredient  by  difference;  or,  (2)  Determine  it  directly 
from  a  second  aliquot  of  the  filtrate  from  the  acetphenetidin  periodid  in  1 2  as  follows : 

Pipette  25-30  cc.  of  the  clear  liquid  into  a  separatory  funnel,  decolorize  with 
solid  sodium  sulphite  and  solid  sodium  bicarbonate  in  slight  excess,  add  1  or  2  drops 
of  acetic  anhydrid,  then  extract  with  three  60  cc.  portions  of  chloroform,  passing 
the  chloroform  solution,  when  cleared,  through  a  small,  dry  filter  into  a  200  cc. 
Erlenmeyer  flask,  and  distil  the  chloroform,  by  the  aid  of  gentle  heat,  to  about  20 
cc.  Add  10  cc.  of  sulphuric  acid  (1  to  10)  and  digest  on  a  steam  bath  until  the  resi- 
due has  been  reduced  one  half,  add  20  cc.  of  water  and  continue  the  digestion  for 
an  hour;  then  add  a  second  20  cc.  portion  of  water  and  10  cc.  of  concentrated  hydro- 
chloric acid,  titrate  very  slowly,  drop  by  drop,  with  the  standard  bromid-bromate  solu- 
tion, 2  (a),  until  a  faint  j^ellow  color  remains.  While  adding  this  reagent,  rotate 
the  flask  sufficiently  to  agglomerate  the  precipitated  tribromanilin.  Calculate  the 
amount  of  acetanilid  present. 

If  the  preparation  contains  caffein  or  antipyrin  or  both  in  addition  to  acet- 
anilid and  acetphenetidin,  proceed  as  follows :'(!)  Digest  the  mixture  by  heating 
with  dilute  sulphuric  acid  to  convert  acetphenetidin  and  acetanilid  to  phenetidin 
and  anilin  sulphates,  respectively;  (2)  Separate  the  caffein  and  antipyrin  by  ex- 
traction with  chloroform;  (3)  Re-form  acetphenetidin  and  acetanilid  by  treat- 
ing the  solution  of  the  corresponding  sulphates  with  solid  sodium  bicarbonate  in 
slight  excess,  then  add  a  few  drops  of  acetic  anhydrid  and  extract  with  chloroform*. 

Acetphenetidin  CPhenacetin)  and  Salol  in  Mixtures^ 
acetphenetidin. 
14  Acid  Hydrolysis  Method. — Tentative. 

Weigh  out  on  a  tared  5.5  cm.  filter"  an  amount  of  the  sample  equal  to,  or  a  mul- 
tiple of,  the  average  weight  of  a  unit  dose  and  wash  with  suflScient  successive,  small 
portions  of  chloroform  to  extract  completely  all  acetphenetidin  and  salol  present 
in  the  mixture  (about  40  cc).  Collect  the  solution  in  a  tared,  100  cc.  beaker  and 
evaporate  on  a  warm  plate  (50°-60°C.)  to  apparent  dryness,  using  an  air  blast. 
Let  stand  24  hours  at  room  temperature  to  practically  constant  weight,  then  trans- 
fer the  crystalline  residue,  by  means  of  chloroform,  to  a  50  cc.  lipped  Erlenmeyer 
flask,  evaporate  the  solvent  by  means  of  an  air  blast  and  gentle  heat,  add  10  cc. 


XXIX]  DRUGS  357 

of  sulphuric  acid  (1  to  10)  and  evaporate  on  the  steam  bath  until  the  volume  is  re- 
duced one  half.  Add  10  cc.  of  water  and  continue  the  digestion  as  before,  then  add 
a  second  10  cc.  of  water  and  evaporate  to  5  cc.  Transfer  the  residue  with  about 
20  cc.  of  water  to  a  small  separatory  funnel  and  extract  with  15,  10  and  5  cc.  of 
chloroform,  washing  each  extract  with  5  cc.  of  water  in  a  second  separatory  funnel 
to  recover  traces  of  phenetidin  sulphate  possibly  dissolved  by  the  chloroform, 
finally  rejecting  the  latter  since  it  contains  all  the  salol  not  previously  eliminated 
during  the  digestion. 

Add  the  wash  water  in  the  second  separatory  funnel  to  the  solution  of  phenetidin 
sulphate  in  the  first  separatory  funnel  and  proceed  as  directed  under  7,  beginning 
with  "Treat  with  successive  small  portions  of  solid  sodium  bicarbonate". 

15  Alkaline  Hydrolysis  Method. — Tentative. 

On  a  small,  tared  filter  weigh  out  an  amount  of  the  sample  to  contain  not  more 
than  0.10  gram  of  salol,  exhaust.with  chloroform  as  directed  in  14,  collect  the  sol- 
vent in  a  small,  lipped  Erlenmeyer  flask  and  evaporate  the  chloroform  by  means  of 
an  air  blast  without  heat.  Add  10  cc.  of  2.5%  sodium  hydro.xid  solution  and  heat  5 
minutes  on  a  steam  bath.  Cool  quickly  to  room  temperature  in  running  water  to 
prevent  partial  hydrolysis  of  the  acetphenetidin.  Transfer  the  liquid  to  a  separa- 
tory funnel  with  a  minimum  of  water,  then  rinse  out  the  flask  with  the  first  20  cc. 
portion  of  chloroform  used  in  the  extraction.  Extract  the  alkaline  solution  with 
three  20  cc.  portions  of  chloroform,  wash  each  portion  in  a  second  separatory  funnel 
with  5  cc.  of  water  and  pass  the  solution  through  a  small,  dry  filter  into  a  200  cc. 
Erlenmeyer  flask.  Designate  the  combined  alkaline  solution  and  washings  as  A. 
Distil  the  combined  chloroform  extracts  to  about  5  cc.  Transfer  by  means  of  a 
little  chloroform  to  a  small,  tared  beaker  or  crystallizing  dish,  evaporate  on  a  steam 
bath  with  the  aid  of  an  air  blast,  cool  and  weigh  the  residual  acetphenetidin  at 
intervals  until  the  weight  becomes  constant. 

SALOL. 

16  Acid  Hydrolysis  Method. — Tentative. 

Subtract  the  weight  of  acetphenetidin,  as  determined  in  14,  from  the  combined 
weight  of  the  2  ingredients  determined  in  14,  to  obtain  the  weight  of  salol. 

1  7  Alkaline  Hydrolysis  Method. — Tentative. 

Place  the  combined  alkaline  solutions.  A,  under  15,  in  a  500  cc.  glass-stoppered 
bottle,  dilute  with  water  to  about  200  cc,  run  in  from  a  burette  an  excess  (about 
45  cc.)  of  N/7  potassium  bromid-bromate,  add  10  cc.  of  concentrated  hydrochloric 
acid  and  shake  1  minute,  then  at  inteivals  for  30  minutes.  Add  10  cc.  of  15%  potas- 
sium iodid  solution  and  shake  at  intervals  for  15  minutes.  Titrate  the  free  iodin 
with  standard  sodium  thiosulphate  solution  (preferably  N/7),  previously  standard- 
ized against  the  N/7  bromid-bromate  solution.  One  cc.  of  N/7  potassium  bromid- 
bromate  is  equivalent  to  2.55  mg.  of  salol.  From  the  number  of  cc.  of  the  N/7 
bromid-bromate  solution  used,  calculate  the  amount  of  salol  on  the  basis  of  12  atoms 
of  bromin  to  1  molecule  of  salol. 

ACETANILID  AND   SODIUM  SALICYLATE  IN  MIXTURES. 
18  PREPARATION  OF  SAMPLE  AND  SOLUTION.-TENTATIVE. 

Weigh  an  amount  of  the  powdered  sample  equal  to,  or  a  multiple  of,  an  average 
unit  dose,  transfer  to  a  separatory  funnel  containing  10  cc.  of  water  and,  for  every 
unit  dose,  add  0.10  gram  of  solid  sodium  bicarbonate.    In  the  case  of  coated  tablets 


358  METHODS    OF   ANALYSIS  [Chap. 

and  pills,  ascertain  their  average  weight,  powder  in  a  mortar  and  weigh  out  an 
amount  of  the  powder  equivalent  to  one  or  more  tablets  or  pills  for  each  determina- 
tion prior  to  treatment  in  the  separatory  funnel.  In  the  examination  of  alcoholic 
preparations,  distil  off  the  alcohol  from  a  measured  volume  on  a  steam  bath, 
transfer  to  a  separatory  funnel  with  a  minimum  of  water  and  add  sufficient  solid 
sodium  bicarbonate  (0.5  to  1.0  gram). 

19  ACETANILID.-TENTATIVE. 

Extract  the  alkaline  solution,  obtained  under  18,  with  three  50  cc.  portions  of 
chloroform,  wash  each  portion  with  5  cc.  of  water  in  a  second  separatory  funnel 
and  collect  the  solvent,  without  previous  drying,  in  a  200  cc.  Erlenmeyer  flask. 
Designate  the  aqueous  solution  as  A.  Distil  off  the  chloroform  very  gently  to 
about  5  cc,  add  10  cc.  of  dilute  sulphuric  acid  and  completely  hydrolyze  on  the 
steam  bath.     Proceed  from  this  point  as  directed  in  4. 

20  SODIUM  SALICYLATE.-TENTATIVE. 

Acidify  the  aqueous  solution  of  sodiiun  salicylate,  A,  under  19,  with  a  few  drops 
of  concentrated  hydrochloric  acid  and  extract  with  sufficient  (3-5)  25  cc.  portions 
of  chloroform  to  exhaust  the  salicylic  acid  present  in  the  mixture.  Treat  each  por- 
tion in  a  second  separatory  funnel  with  20  cc.  of  water,  containing  1  gram  of 
anhydrous  sodium  carbonate  for  every  100  mg.  of  salicylic  acid.  Shake  vigorously 
and,  after  clearing,  wash  each  portion  again  in  a  second  separatory  funnel  with  5  cc. 
of  water,  then  add  the  washings  to  the  main  aqueous  soda  solution  of  sodium 
salicylate.  Dilute  to  a  known  volume,  transfer  an  aliquot,  representing  about  100 
mg.  of  salicylic  acid,  to  a  200  cc.  Erlenmeyer  flask,  make  up  to  100  cc,  heat  nearly 
to  boiling,  then  run  in  from  a  burette  25-40  cc.  of  strong  (about  N/5)  iodin  solu- 
tion, sufficient  to  insure  an  excess  during  digestion  and  digest  for  an  hour  on  a  steam 
bath.  Remove  the  free  iodin  with  a  few  drops  of  sodium  thiosulphate  solution, 
decant  the  clear  liquid  through  a  tared  Gooch,  retaining  most  of  the  precipitate, 
tetraiodophenylenquinon  (C6H2l20)2,  in  the  flask.  To  the  latter  add  50  cc.  of 
boiling  water,  digest  10  minutes  on  the  steam  bath,  then  filter,  wash  gradually 
all  the  precipitate  into  a  Gooch,  using  for  this  purpose  and  the  final  washing 
about  200  cc.  of  hot  water.  Dry  to  constant  weight  in  an  air  bath  at  100°C.  Mul- 
tiply the  weight  of  the  precipitate  by  0.4654  to  obtain  the  quantity  of  sodium 
salicylate  present  in  the  aliquot  taken. 

Should  the  mixture  contain  caffein  or  antipyrin,  or  both,  these  substances  will 
appear  with  the  acetanilid  in  the  first  chloroform  extract  and  may  be  determined 
as  directed  in  the  closely  set  type  following  10.  Should  the  acetanilid  be  replaced  by 
acetphenetidin  in  the  mixture,  the  general  procedure  would  not  be  materially  altered, 
the  acetphenetidin  being  weighed  directly  after  recovery  from  its  washed  chloro- 
form solution  as  separated  from  the  sodium  salicylate.  If,  instead  of  sodium  sal- 
icylate, the  mixture  contains  the  free  acid  or  its  ammonium  salt,  add  a  larger  quan- 
tity of  sodium  bicarbonate  prior  to  extraction  with  chloroform  to  insure  the  fixation 
of  salicylic  acid. 

In  the  analysis  of  a  mixture  of  caffein,  acetanilid,  sodium  salicylate  and  codein 
sulphate,  the  following  procedure  is  recommended:  (1)  Extraction  of  caffein,  acet- 
anilid and  salicylic  acid  from  the  acidified  solution;  (2)  Washing  the  chloroform 
solution  with  aqueous  soda  solution  for  the  recovery  of  salicylic  acid,  preliminary 
to  its  treatment  with  iodin  solution;  (3)  Separation  of  caffein  and  acetanilid  as 
directed  under  3  and  4;  (4)  Recovery  of  codein  from  the  solution  of  its  sulphate 
after  treatment  with  sodium  bicarbonate  and  chloroform. 


XXIX]  DRUGS  359 

Caffein,  Acetanilid  and  Quinin  Sulphate  in  Mixtures. 

21  preparation  of  sample  and  solution.-tentative. 

Transfer  to  a  scparatory  funnel  one  or  more  average  unit  doses  of  the  powdered 
sample,  add  20  cc.  of  water  and  50  cc.  of  chloroform,  then  10  drops  of  dilute  sulphuric 
acid  and  extract  in  the  usual  way.  After  clearing,  wash  the  solvent  in  a  second 
separatory  funnel  with  5  cc.  of  water  prior  to  transferring  to  a  200  cc.  Erlenmeyer 
flask.  Repeat  the  foregoing  operations  with  two  50  cc.  portions  of  chloroform, 
finally  distilling  the  combined  chloroform  solution  to  about  10  cc.  by  gentle  heat. 

22  CAFFEIN  AND  ACETANILID.— TENTATIVE. 

Treat  the  chloroform  residue  obtained  in  21  as  directed  under  3  and  4. 

23  QUININ  SULPHATE.— TENTATIVE. 

Combine  the  wash  water,  used  in  the  second  separatory  funnel  in  21,  with  the 
solution  of  quinin  bisulphate,  add  a  slight  excess  of  solid  sodium  bicarbonate,  ex- 
tract with  three  50  cc.  portions  of  chloroform,  wash  each  portion  with  5  cc.  of  water 
in  a  second  separatory  funnel  and  then  pass  through  a  dry  filter  into  a  200  cc.  Erlen- 
mej^er  flask.  Distil  by  gentle  heat  to  about  5  cc,  evaporate  on  a  steam  bath 
to  apparent  dryness,  dissolve  the  amorphous  alkaloid  in  5  cc.  of  neutral  alcohol 
and  titrate  with  N/50  hydrochloric  acid  to  a  faint  red,  using  2  drops  of  methyl  red 
as  an  indicator.  Heat  on  a  steam  bath  until  most  of  the  alcohol  has  been  expelled, 
adding,  if  necessary,  sufficient  acid  to  maintain  the  acid  reaction.  From  the  total 
number  of  cc.  of  acid  employed  in  the  titration  calculate  the  quinin  sulphate.  One 
cc.  of  N/50  hydrochloric  acid  is  equivalent  to  8.73  mg.  of  quinin  sulphate. 

If  the  mixture  contains  acetphenetidin  in  place  of  acetanilid,  proceed  as  out- 
lined above,  except  that  the  separation  of  caffein  and  acetphenetidin  is  conducted 
as  directed  under  6  and  7. 

Caffein,  Acetanilid  and  Codein  Sulphate  in  Mixtures. 

24  prspar\tio.v  o?  s\m?l3  axd  sdlunox.-tsxrative. 
Proceed  as  directed  under  21 . 

25  caffein  and  acetanilid. -tentative. 
Proceed  as  directed  under  22. 

26  CODEIN  sulphate.— tentative. 

Proceed  as  directed  under  23  to  the  point  indicated  by  the  sentence  "Distil  by 
gentle  heat  to  about  5  cc".  Transfer  the  chloroform  solution  of  codein  with  suffi- 
cient solvent  to  a  small,  tared  beaker,  evaporate  to  apparent  dryness  on  a  steam 
bath,  add  a  few  drops  of  alcohol  to  the  amorphous  residue,  then  a  like  amount  of 
water  and  evaporate  again.  Finally  cool  and  allow  the  usually  crystalline  product 
to  stand  until  the  weight  becomes  constant.  The  weight  of  this  residue  multiplied 
by  1.3144  gives  the  quantity  of  codein  sulphate  present. 

This  result  should  be  checked  volumctrically.  Dissolve  the  residue  in  3-5  cc.  of 
neutral  alcohol  and  titrate  with  N/50  sulphuric  acid  to  a  faint  red,  using  methyl 
red  as  an  indicator.  From  the  number  of  cc.  of  standard  acid  employed  calculate 
the  amoimt  of  codein  sulphate.  Ojic  cc.  of  N/50  sulphuric  acid  is  equivalent  to 
7.87  rag.  of  codein  sulphate.  The  quantity  of  codein  sulphate  as  found  by  weight 
will  usually  be  slightly  greater  than  that  determined  by  titration. 


360  METHODS    OF   ANALYSIS  [Chap, 

Caffein,  Acetanilid,  Quinin  Sulphate  and  Morphin  Sulphate  in  Mixtures. 

27  preparation  of  sample  and  solution.— tentative. 

Transfer  to  a  separatory  funnel  an  amount  (containing  not  less  than  one  fourth 
grain  of  morphin)  of  the  powdered  sample  equal  to,  or  a  multiple  of,  a  unit  dose, 
add  20  cc.  of  water  and  10  drops  of  dilute  sulphuric  acid,  then  extract  with  three 
50  cc.  portions  of  alcohol-free  chloroform,  wash  each  portion  in  a  second  separatory 
funnel  with  5  cc.  of  water  and  add  the  combined  washings  to  the  alkaloidal  solu- 
tion in  the  first  separatory  funnel.  Filter  the  chloroform  extracts  through  a  small, 
dry  filter  into  a  200  cc.  Erlenmeyer  flask  and  distil  by  gentle  heat  to  about  10  cc. 

28  CAFFEIN  AND  ACETANILID.— TENTATIVE. 
Treat  the  chloroform  residue  as  directed  under  3  and  4. 

29  QUININ  SULPHATE.— TENTATIVE. 

Add  to  the  solution  of  quinin  and  morphin  sulphates,  obtained  in  27,  4-5  cc.  of 
sodium  hydroxid  solution  (1  to  10)  and  extract  with  four  40  cc.  portions  of  chloro- 
form, wash  each  portion  with  5  cc.  of  water  and  pass  the  clear  solvent  through  a 
small,  dry  filter  into  a  200  cc.  Erlenmeyer  flask.  Remove  the  solvent  by  gentle 
distillation  and  titrate  the  residual  quinin  with  N/50  hydrochloric  acid  as  directed 
under  23. 

30  MORPHIN  SULPHATE.-TENTATIVE. 

Wash  the  filter,  employed  in  29,  with  5  cc.  of  water  and  add  to  the  aqueous 
alkaline  solution  of  the  alkaloid.  Now  add  0.5  gram  of  ammonium  chlorid  (or  an 
amount  slightly  in  excess  of  that  required  to  free  the  morphin  as  well  as  convert 
all  sodium  hydroxid  to  sodium  chlorid)  and,  to  the  resulting  ammoniacal  solution, 
add  45  cc.  of  chloroform  and  5  cc.  of  alcohol,  then  extract  in  the  usual  way,  washing 
the  solvent  in  a  second  separatory  funnel  with  5  cc.  of  water.  After  clearing,  pass 
the  chloroform  through  a  small,  dry  filter  into  a  200  cc.  Erlenmeyer  flask.  Repeat 
the  extraction  with  three  40  cc.  portions  of  chloroform,  washing  and  filtering  as  be- 
fore, finally  collecting  all  the  solvent  in  an  Erlenmeyer  flask  and  distilling  to  about 
10  cc.  Transfer  with  chloroform  to  a  small,  tared  beaker,  evaporate  to  apparent 
dryness,  add  0.5  cc.  each  of  water  and  neutral  alcohol,  start  crystallization  by 
stirring  with  a  glass  rod  and  finally  evaporate  to  dryness.  Cool  and  allow  to  stand 
until  the  weight  becomes  constant. 

Check  the  weight  of  morphin,  thus  determined,  by  titration  with  N/50  sulphuric 
acid,  using  a  drop  of  methyl  red  as  an  indicator.  Dissolve  the  alkaloid  in  1-2  cc. 
of  warm,  neutral  alcohol,  then  add  the  standard  acid  to  a  faint  red.  Evaporate 
most  of  the  alcohol  on  a  steam  bath,  adding,  if  necessary,  sufficient  acid  to  main- 
tain the  acid  reaction.  From  the  volume  of  acid  used  calculate  the  morphin  sul- 
phate.   One  cc.  of  N/50  sulphuric  acid  is  equivalent  to  7.58  mg.  of  morphin  sulphate. 

Tragacanth. 

31  VOLATILE  ACIDITY^.— tentative. 

The  quantity  of  volatile  (acetic)  acidity  developed  in  the  acid  hydrolysis  of  gum 
tragacanth  {Astragalus  gummijer)  affords  a  valuable  index  of  the  purity  of  this  com- 
modity when  compared  with  results  obtained  by  similar  treatment  of  so-called 
"Indian  gum"  {Cochlospernum  gossypium  and  Sterculia  urens).  The  term  "vola- 
tile acidity"  expresses  the  nmnber  of  cc.  of  N/10  potassium  or  sodium  hydroxid 
required  to  neutralize  the  volatile  (acetic)  acid  obtained  by  distilling  with  steam 
the  products  of  the  action  of  boiling  aqueous  phosphoric  acid  on  1  gram  of  the  gum. 


XXIXJ  DRUGS  361 

Treat  1  gram  of  the  whole  or  powdered  sample  in  a  700  cc.  round-bottomed,  long- 
necked  flask  for  several  hours  in  the  cold  with  100  cc.  of  water  and  5  cc.  of  sirupy 
phosphoric  acid  until  the  gum  is  completely  swollen.  Boil  gentlj'  for  2  hours  under 
a  reflux  condenser.  A  very  small  amount  of  cellulose  substance  will  remain  undis- 
solved. Now  distil  the  hydrolyzed  product  with  steam,  using  a  spray  trap'  to  con- 
nect the  distillation  flask  with  the  condenser  and  continue  until  the  distillate 
amounts  to  600  cc.  and  the  acid  residue  to  about  20  cc.  Do  not  concentrate  too  far, 
as  this  would  scorch  the  non-volatile,  organic  decomposition  products  and  possibly 
contaminate  the  distillate.  Titrate  the  distillate  with  N/10  potassium  hydroxid, 
using  10  drops  of  phenolphthalein  as  an  indicator,  finally  boiling  the  liquid  under 
examination  until  a  faint  pink  color  remains.  Correct  the  result  by  a  blank  de- 
termination and  express  the  final  result  in  terms  of  the  number  of  cc.  of  N/10 
alkali  required,  as  in  the  above  definition. 

While  tragacanth  yields  a  practically  colorless  solution  when  boiled  with  aqueous 
phosphoric  acid,  Indian  gum,  on  the  other  hand,  gives  a  pink  or  rose  solution.  This 
reaction  may  be  used  as  a  preliminary  test  for  the  detection  of  Indian  gum. 

Levant  Wormseed. 

32  santonin.— tentative. 

Extract  10  grams  of  the  sample,  ground  to  pass  a  30  mesh  sieve,  in  a  Soxhlet  ex- 
traction apparatus  for  3  hours  with  chloroform.  Distil  oflf  the  chloroform  until 
7-8  cc.  remain;  add  100  cc.  of  5%  barium  hydro.xid  solution  and  heat  on  a  steam 
bath  until  the  odor  of  chloroform  has  disappeared.  Boil  5  minutes,  cool  and  pass 
carbon  dioxid  (washed  through  sodium  bicarbonate  solution  to  remove  traces 
of  acid)  until  saturated.  Filter  on  a  small  Biichner  funnel,  using  suction,  and  wash 
twice  with  10  cc.  of  water.  Heat  the  filtrate  on  a  steam  bath,  add  5  cc.  of  25% 
hydrochloric  acid  and  warm  5  minutes.  Cool  until  lukewarm  and  extract  with  20, 
15  and  15  cc.  of  chloroform,  passing  the  solvent  through  a  small  filter  into  a  flask. 
Evaporate  to  dryness,  removing  the  last  traces  of  chloroform.  Dissolve  in  7.5 
grams  (9.5  cc.)  of  absolute  alcohol,  warming  gently  if  necessary.  Then  add  42.5 
cc.  of  water  heated  to  60°-70°C.,  stopper  the  flask  and  allow  to  cool.  Start  crystal- 
lization at  this  point  by  scratching  the  side  of  the  flask  with  a  rod  or  by  seeding  with 
a  minute  crystal  of  santonin.  (Solutions  containing  a  liberal  amount  of  santonin, 
kept  in  a  cool  place  for  24  hours,  have  been  found  in  a  supersaturated  condition 
where  this  precaution  was  not  observed.)  Maintain  the  flask  and  contents  at  a 
temperature  of  15°-17°C.  for  24  hours.  Filter  and  wash  at  15''-17°C.  with  two  10 
cc.  portions  of  15%  alcohol  by  weight.  Dry  the  flask  and  filter  at  100°C.,  dis- 
solve the  santonin  left  in  the  flask  and  on  the  filter  in  chloroform  and  filter  into  a 
tared  beaker.  Wash  the  flask  and  paper  thoroughly  with  chloroform,  evaporate 
the  combined  filtrate  and  washings,  dry  at  100°C.  to  remove  all  traces  of  chloroform 
and  weigh.  To  the  weight  found  add  0.04  gram  for  the  santonin  dissolved  in  the 
dilute  alcohol  and  multiplj'  the  total  by  10  to  obtain  the  per  cent  of  santonin. 

Nitroglycerin  in  Tablets. 

33  preparation  of  sample.-tentative. 

(a)  Crush  25  tablets  under  10  cc.  of  anhydrous  ether  in  a  25  cc.  cylinder  by 
means  of  a  stout  glass  rod.  Rinse  the  rod  with  a  little  anhydrous  ether,  allow 
the  insoluble  material  ^o  settle  and  decant  the  solution  into  a  50  cc.  jjraduated 
flask.  Wash  the  residue  repeatedly  with  5  cc.  portions  of  anhydrous  ether,  decant 
the  washings  into  the  flask  until  it  is  filled  to  the  mark,  stopper  and  mix  well. 
Designate  this  solution  as  .1. 


362  METHODS    OF   ANALYSIS  [Chap. 

Add  10  cc.  of  water  to  the  residue,  mix  Vv^ell  and  transfer  the  mixture  to  a 
small  separatory  funnel  by  means  of  a  little  water.  Extract  with  3  successive 
portions  of  10,  5  and  5  cc.  of  ether.  Collect  the  ether  extracts  in  a  50  cc.  beaker 
and  designate  this  solution  as  B. 

(b)  Dis'ntegrate  25  tablets  in  a  small  beaker  with  10  cc.  of  water,  breaking 
up  any  lumps  with  a  glass  rod,  and  transfer  by  means  of  a  little  water  to  a  sepa- 
ratory funnel.  Rinse  the  beaker  with  10  cc.  of  ether  and  transfer  this  also  to  the 
funnel.  Shake  thoroughly,  draw  off  the  aqueous  layer  and  transfer  the  ether 
through  a  funnel,  containing  a  little  cotton,  to  a  50  cc.  graduated  fiask.  Repeat 
the  extraction  with  successive  portions  of  ether  until  the  flask  is  filled  to  the  mark, 
stopper  and  mix  well.     Designate  this  solution  as  C. 

In  hand-made  and  soft  compressed  tablets,  the  method  described  under  fa)  is 
preferred,  since  the  direct  extraction  of  the  dry  crushed  material  with  ether  re- 
moves most  of  the  nitroglycerin.  In  hard  compressed  tablets,  the  direct  extraction 
is  often  not  nearly  so  complete  and,  in  such  cases,  the  method  described  under  (b) 
is  to  be  preferred. 

Nitrate  Method^. — Tentative. 

34  REAGENTS. 

(a)  Phenoldisulphonic  acid  solution. — Prepare  as  directed  under  IV,  14  (a). 

(b)  Standard  nitrate  solution.—Dissolve  0.7217  gram  of  potassium  nitrate  in  1 
liter  of  water.  Evaporate  10  cc.  of  this  solution  just  to  dryness  in  a  porcelain  dish 
on  a  steam  bath.  Cool  and  treat  the  residue  with  2  cc.  of  the  phenoldisulphonic 
acid  solution,  rubbing  with  a  glass  rod  to  insure  intimate  contact.  After  5-10  min- 
utes dilute  to  250  cc.  Each  cc.  of  this  solution  contains  0.004  mg.  of  nitrogen.  Add 
an  excess  of  potassiiun  hydroxid  solution  to  an  aliquot  of  this  solution  and  dilute 
to  100  cc.  (Do  not  use  sodium  or  ammonium  hydroxid.)  It  is  advisable  to  pre- 
l)are  a  standard  of  approximately  the  same  color  as  the  unknown. 

35  DETERMINATION. 

Place  20  cc.  of  the  ether  solution,  A  or  C  under  33,  in  a  dried,  tared  50  cc.  beaker. 
Evaporate  the  solvent  in  a  vacuum  desiccator  containing  sulphuric  acid.  Apply 
the  vacuum  gradually,  to  prevent  boiling.  Allow  the  beaker  to  remain  in  the 
vacuum  30  minutes  after  the  ether  has  evaporated.  Weigh  and  calculate  the  ether 
extract  per  tablet.  Treat  the  residue  with  2  cc.  of  the  phenoldisulphonic  acid  solu- 
tion, rotating  the  beaker  so  that  the  reagent  comes  in  contact  with  the  entire  inner 
surface.  After  10  minutes  add  water  and  wash  into  a  100  cc.  flask.  Dilute  to  the 
mark  and  place  10  cc,  representing  1  tablet,  in  a  100  cc.  flask,  add  about  50  cc.  of 
water  and  a  few  drops  more  of  20%  potassium  hydroxid  solution  than  is  required  to 
neutralize  the  acid.  Dilute  to  the  mark  and  compare  the  color  with  that  pro- 
duced when  a  standard  nitrate  solution  is  similarly  treated.  Any  convenient  col- 
orimeter or  Nessler  tubes  may  be  used.  Multiply  the  nitrate  nitrogen  found  by 
5.4  to  obtain  the  equivalent  of  nitroglycerin. 

When  33  (a)  is  used  for  the  p.eparat'on  of  the  sample,  a  correction,  deter- 
mined as  directed  in  37,  should  be  made  for  the  amount  of  nitroglycerin  in  B 
under  33,  using  all  of  B  instead  of  an  aliquot. 

Nitrite  or  Modified  Hay  Method^ .—Tentative. 

36  REAGENTS. 

(a)  Sulphanilic  acid  solution. — Prepare  as  directed  under  IV,  12  (b). 

(b)  Alpha-naphlhylamin  hydrochlorid  solution. — Prepare   as  directed  under  IV, 

12  (c). 


XXIX]  DRUGS  363 

(C)  Standard  nitrite  solution. —S^c\g\\  out  0.220  gram  of  dry  silver  nitrite  [XV, 
18  (c)],  dissolve  in  a  small  quantity  of  hot  water  and  decompose  with  a  slight  ex- 
cess of  sodium  chlorid  solution.  When  the  solution  becomes  clear,  dilute  to  1  liter 
with  nitrite-free  water.  Dilute  5  cc.  of  this  solution  to  1  liter  with  nitrite-free  water. 
The  second  dilution,  containing  0.0001  mg.  of  nitrous  nitrogen  per  cc,  is  the  stand- 
ard to  be  used.     [Cf.  IV,  12  (d)] 

37  DETERMINATION. 

Place  5  cc.  of  the  ether  solution,  A  or  C  under  33,  in  a  50  cc.  beaker 
dilute  with  5-10  cc.  of  alcohol  and  add  about  5  cc.  of  0.5%  alcoholic  potassium  hy- 
droxid.  Cover  with  a  watch  glass  and  allow  to  stand  10  minutes.  Place  on  a  steam 
bath,  boil,  remove  the  watch  glass  and,  when  most  of  the  liquid  has  evaporated,  add 
about  25  cc.  of  water  and  return  to  the  steam  bath  until  about  half  the  liquid  has 
evaporated  or  until  the  odor  of  alcohol  can  no  longer  be  detected.  Cool  and  dilute 
with  nitrite-free  Avater  to  250  cc.  Each  cc.  of  this  solution  represents  0.01  of  a 
tablet.  Introduce  an  aliquot,  representing  0.02-0.04  mg.  of  nitroglycerin,  into  a 
100  cc.  graduated  flask,  dilute  with  sufficient  nitrite-free  water  to  make  the  volume 
90-95  cc,  add  a  drop  of  concentrated  hydrochloric  acid,  then  2  cc.  of  the  sulphanilic 
acid  solution  and  2  cc.  of  the  alpha-naphthylamin  hydrochlorid  solution.  Com- 
plete the  volume  with  nitrite-free  water.  Prepare  at  the  same  time  and  in  the  same 
manner  standards  containing  known  amounts  of  sodium  nitrite.  Stopper  the  flasks, 
mix  well  and  compare  the  colors  after  30  minutes,  using  any  convenient  colorimeter 
or  Nessler  tubes.  Multiply  the  nitrite  nitrogen  found  by  the  factor  8,  which  has 
been  determined  experimentally,  to  obtain  the  equivalent  of  nitroglycerin. 

When  33  (a)  i.s  used  for  the  preparation  of  the  sample,  a  correction,  deter- 
mined as  directed  above,  should  be  made  for  the  amount  of  nitroglycerin  in  B 
under  33,  using  all  of  B  instead  of  an  aliquot. 

Pepsin  in  Liquids.-tentative. 

38  REAGENTS. 

(a)  Standard  pepsin. — Powder  a  good  grade  of  U.  S.  P.  pepsin  and  pass  it  through 
a  No.  60  sieve;  dry  in  vacuo  over  calcium  chlorid,  again  pass  through  a  sieve  and 
preserve  in  a  stoppered  bottle.  Ascertain  the  exact  pepsin  equivalent  of  the  dry 
powder  by  the  U.  S.  P.  method'"  and  express  in  percentage  based  on  the  assaraptiou 
that  the  U.  S.  P.  product  is  100%  pure. 

(b)  Standard  pepsin  solutions. — Weigh  off  definite  amounts  of  the  standard  pep- 
sin into  the  requisite  quantity  of  N/10  hydrochloric  acid  to  make  solutions  con- 
taining 5  and  0.5  mg.  of  pepsin  per  cc.     These  should  be  freshly  prepared. 

(C)  Ricin  solulion. — Grind  commercial  ricin,  similar  to  the  "Ricin  Prepiirat  nach 
Jacoby",  to  a  No.  60  powder,  mix  thoroughly,  dry  and  keep  in  a  desiccator.  Digest 
1  gram  of  this  powder  for  an  hour  at  37.5°C.  in  100  cc.  of  5%  sodium  chlorid  solution, 
cool,  filter  and  use  at  once  for  the  assay. 


PREPARATION   OF  SOLUTIONS. 


39 

(a)  Dilute  solulion  of  the  sample. — Dilute  the  sample  with  a  measured  amount  of 
N/10  hydrochloric  acid  until,  upon  digestion  at  37.5°C.,  1  cc.  requires  approximately 
15  minutes  to  digest  the  precipitate  obtained  by  mixing  2  cc.  of  the  ricin  solution 
and  0.5  cc.  of  N/10  h3'drochloric  acid.  To  50  cc.  of  this  diluted  preparation  add  the 
requisite  quantity  of  water  or  of  N/5  hj'drochloric  acid  to  make  the  preparation  of 
N/10  acid  strength  when  diluted  with  N/10  acid  to  90  cc.     Preserve  the  sample  in 


364  METHODS    OF   ANALYSIS  [Chap. 

a  refrigerator.  (Solid  pepsin  preparations  may  often  be  extracted  with  hydro- 
chloric acid  of  appropriate  strength  and  prepared  for  assay  in  the  same  manner.) 

(b)  Dilute  comparison  solution  of  the  sample. — Add  1  cc.  of  N/10  hydrochloric 
acid  to  9  cc.  of  the  dilute  solution  of  the  sample. 

(C)  Dilute  inactive  solution  of  the  sample. — Immerse  a  stoppered  glass  vessel,  con- 
taining 45  cc.  of  the  dilute  solution  of  the  sample  and  5  cc.  of  N/10  hydrochloric 
acid,  in  boiling  water  for  15  minutes  and  filter. 

(d)  Standard  solution  containing  0.5  mg.  of  active  U.  S.  P.  pepsin  per  cc. — Im- 
merse a  stoppered  test  tube  containing  18  cc.  of  the  dilute  solution  of  the  sample 
in  boiling  water  for  10  minutes  and,  after  cooling,  add  2  cc.  of  the  standard  pepsin 
solution,  containing  5  mg.  of  pepsin  per  cc,  and  filter  if  necessary. 

If  the  solutions  to  be  tested  are  not  clear,  filter  through  hardened  filters.  If, 
however,  they  cannot  thus  be  clarified,  make  check  comparison  tubes  containing 
the  same  amounts  of  the  preparation  made  up  in  the  same  way  with  2  cc.  of  water 
in  place  of  the  ricin  solution  used  in  the  determination. 

40  DETERMINATION. 

To  each  of  15  tubes,  add  from  a  burette  2  cc.  of  the  ricin  solution  and  0.5  cc.  of 
N/10  hydrochloric  acid,  heat  to  37.5°C.  and  add  the  following  quantities  of  the 
solutions: 

To  the  first  5  tubes,  add  0.00-1.00  cc.  of  the  dilute  comparison  solution  of  the 
sample  in  0.25  cc.  increments,  and  1.00-0.00  cc.  of  the  dilute  inactive  solution  of 
the  sample  in  0.25  cc.  decrements.  To  the  next  5  tubes,  add  1.00-0.00  cc.  of  the 
dilute  inactive  solution  of  the  sample  in  0.25  cc.  decrements  and  0.00-1.00  cc.  of  the 
standard  solution  containing  0.5  mg.  of  active  U.  S.  P.  pepsin  per  cc.  in  0.25  cc. 
increments.  To  the  last  5  tubes,  add  1.00-0.00  cc.  of  N/10  hydrochloric  acid  in 
0.25  cc.  decrements  and  0.00-1.00  cc.  of  the  standard  pepsin  solution  containing  0.5 
mg.  of  pepsin  per  cc.  in  0.25  cc.  increments. 

By  comparing  any  tube  of  the  first  group  of  5  with  the  tubes  in  the  remaining 
groups  the  degree  of  proteolytic  activity  of  the  dilute  comparison  solution  of  the 
sample  may  be  matched  against  known  amounts  of  standard  pepsin  both  in  ordi- 
nary acid  medimn,  last  group  of  5,  and  in  the  same  medium  as  the  sample  itself, 
second  group. 

Introduce  the  acid  and  the  dilute  inactive  solution  of  the  sample  into  the  tubes 
first  and  then  pour  in  the  solutions  to  be  tested  as  rapidly  as  possible  from  gradu- 
ated pipettes,  noting  the  total  time  consumed  in  the  process  after  adding  the  pepsin. 

After  the  addition  of  the  solution  to  be  tested,  again  immerse  the  test  tubes  in 
the  37.5°C.  bath,  preferably  arranged  in  corresponding  order  in  a  partitioned  square 
or  oblong  wire  rack,  such  as  is  used  in  bacteriological  work.  Shake  and  examine  the 
tubes  from  time  to  time  for  1-2  hours,  noting  the  time  when  the  digestion  begins 
and  ends.  In  case  of  very  weak  solutions  they  may  be  allowed  to  digest  over- 
night. 

If  the  rate  of  digestion  is  the  same  in  each  group,  the  dilute  comparison  solution 
of  the  sample  contains  exactly  0.5  mg.  of  pepsin  per  cc.  If  the  rate  is  more  rapid 
in  the  first  group  than  in  the  others,  it  is  stronger,  the  comparative  strength  being 
closely  indicated  by  the  time  of  action  in  the  tube  containing  less  of  the  solution. 
If  the  rate  of  clearing  is  more  rapid  in  the  last  group  than  in  the  second,  some  in- 
terfering substance  is  present  and  must  be  removed  by  dialysis,  or  by  evaporation 
in  vacuo  at  a  low  temperature  until,  upon  re-examination  and  further  dilution  or 
concentration,  the  rate  of  digestion  is  identical  or  nearly  so  in  each  series. 

Smaller  quantities  of  pepsin  may  be  determined  in  the  same  way  by  comparing 


XXIX]  DRUGS  365 

them  with  more  dilute  solutions  of  standard  pepsin.  Thus  0.05  mg.  of  U.  S.  P. 
pepsin  can  be  readily  detected  by  the  nearly  complete  solvent  action  on  the  ricin 
precipitate  in  less  than  2  hours.  A  marked  action  on  the  ricin  within  the  same  time 
is  shown  by  0.005  mg.  For  all  practical  purposes  the  absence  of  an  appreciable  sol- 
vent action  after  4  hours  digestion  indicates  the  absence  of  pepsin.  Express  the  re- 
sult in  per  cent,  assuming  U.  S.  P.  pepsin  to  be  100%  pure  and  calculating  the 
result  according  to  the  dilution  found  necessary  in  preparing  the  dilute  solution 
of  the  sample. 

Turpentine. 

41  color.-tentative. 

Fill  a  200  cc.  flat-bottomed  colorimeter  tube,  graduated  in  mm.,  to  a  depth  of 
40-50  mm.  with  the  turpentine.  Place  the  tube  in  a  colorimeter  and  place  on  or 
under  it  a  No.  2  yellow  Lovibond  glass.  Over  or  under  a  second  graduated  tube 
in  the  colorimeter,  place  a  No.  1  yellow  Lovibond  glass  and  run  in  the  same  turpen- 
tine until  the  color  matches  as  nearly  as  possible  the  color  in  the  first  tube.  Read 
the  difference  in  depth  of  the  turpentine  in  the  2  tubes.  If  this  difference  is  50  mm. 
or  more,  the  turpentine  is  "standard". 

42  SPECIFIC  GRAVITY.-TENTATIVE. 

20°  C 
Determine  the  specific  gravity  at  -p— ^  by  means  of  a  pycnometer.     The  specific 

gravity  may  also  be  determined  somewhat  less  accurately  at  any  convenient  tem- 
perature with  a  plummet,  correcting  the  result  by  using  the  factor  0.00082  for  each 
degree  that  the  temperature  of  the  determination  differs  from  the  standard  tem- 
perature. 

43  REFRACTIVE  INDEX.-TENTATIVE. 

Determine  the  refractive  index  at  any  convenient  temperature  with  an  accurate 
instrument  and  calculate  the  result  to  20°C.,  using  the  correction  factor  0.00045 
for  each  degree  that  the  temperature  of  the  determination  differs  from  20°C. 

44  DISTILLATION.-TENTATIVE. 

Use  an  ordinary  Engler  flask  (the  internal  diameter  of  the  side  tube  must  be  6-7 
mm.)  and  condenser'*  and  heat  the  flask  in  a  glycerin  or  oil  bath'^.  Fit  the  flask 
with  a  thermometer  reading  145°-200°C.  Place  100  cc.  of  the  turpentine  in  the 
flask,  connect  with  the  condenser  and  distil.  Conduct  the  distillation  so  that  the 
distillate  passes  over  at  the  rate  of  2  drops  per  second.  Note  the  initial  distilling 
temperature  and  the  percentage  distilling  below  170°C. 

POLYMERIZATION. -TENTATF/E. 

45  REAGENT. 

S8N  sulphuric  acid. — Mix  140  grams  of  concentrated  sulphuric  acid  with  suflBcient 
liquid,  fuming  sulphuric  acid  (about  10  grams)  to  obtain  an  acid  slightly  stronger 
than  38N.  Determine  the  exact  strength'*  of  this  mixture  and  also  of  the  concen- 
trated acid  as  follows:  Weigh  out  6-8  grams  in  a  bulb,  having  a  capillary  tube  in  the 
lower  end  and  a  tube  with  a  stop-cock  in  the  upper  end,  fitted  with  a  platinimi 
wire  for  suspending  on  a  balance.  (The  bulb  is  filled  by  the  aid  of  a  slight  vacuum, 
and  the  lower  end  of  the  capillary  is  emptied  by  closing  the  stop-cock  simultaneously 
with  the  withdrawal  of  the  capillary  from  the  acid;  after  which  it  is  wiped  off  first 
with  a  wet  and  then  with  a  dry  piece  of  cloth.)  Run  the  acid  into  cold  water,  make 
up  to  volume  and  titrate  an  aliquot  of  the  solution  against  standard  alkali  or  add  an 


366  METHODS    OF   ANALYSIS 

excess  of  ammonium  hydroxid  to  an  aliquot,  evaporate  to  dryness,  dry  to  constant 
weight  at  120°-130°C.  and  weigh  as  ammonium  sulphate.  Calculate  the  sulphur 
trioxid  content  of  the  acid  and  add  sufficient  concentrated  sulphuric  acid  to  make 
it  exactly  82.38%  of  SO3.  The  acid  must  be  carefully  protected  against  absorption 
of  water  from  the  air. 

46  DETERMINATION. 

Place  20  cc.  of  the  38N  sulphuric  acid  (100.92%)  in  a  graduated,  narrow-necked 
Babcock  flask,  stopper,  place  in  ice  water  and  cool.  Add  slowly  5  cc.  of  the  turpen- 
tine. Mix  the  contents  gradually,  cool  from  time  to  time  and  do  not  allow  the  tem- 
perature to  rise  above  60°C.  When  the  mixture  no  longer  warms  up  on  shaking,  agi- 
tate thoroughly,  place  in  a  water  bath  and  heat  to  60°-65°C.  for  about  10  minutes, 
keeping  the  contents  of  the  flask  thoroughly  mixed  by  vigorous  shaking  5-6  times. 
Cool  to  room  temperature  and  fill  the  flask  with  concentrated  sulphuric  acid  until 
the  unpolymerized  oil  rises  into  the  graduated  neck.  Centrifugalize  4—5  minutes  at 
about  1200  revolutions  per  minute,  or  allow  to  stand  for  12  hours.  Read  the  un- 
polymerized residue,  notice  its  consistency  and  color  and  determine  its  refractive 
index. 

BIBLIOGRAPHY. 

»  U.  S.  Bur.  Chem.  Bull.  152,  p.  239. 

2  .1.  Ind.  Eng.  Chem.,  1915,  7:  519. 

3  Ibid..  1914,  6:665. 

*  U.  8.  Bur.  Chem.  Bull.  162,  p.  197. 

*>  J.  Ind.  Eng.  Chem.1915,  7:  681. 

"Ibid.,  1912,  4:374. 

■<  U.  S.  Bur.  Chem.  Circ.  94,  p.  4. 

8  Am.  J.  Pharm.,  1911,  83:  359. 

3  Trans.  Roy.  Soc.  Edinburgh,  1885,  32:  67. 
i«  U.  S.  P.,  VIII,  1905,  p.  334. 

"  Stillman.  Engineering  Chemistry.  4th  ed.,  1910,  p.  503. 
«  U.  S.  Bur.  Chem.  Bull.  135,  p.  2(3. 
13  U.  S.  Bur.  Chem.  Circ.  85,  p.  12. 


INDEX 

Abrastol 151 

Acetanilid 352,  356,  358,  359,  360 

and  acetphenetidin,  in  mixtures 354 

sodium  salicylate,  in  mixtures 357 

Acetphenetidin  (phenacetin) 353,  354,  356 

and  salol,  in  mixtures 356 

Acetyl  value,  of  fats  and  oils 310 

Acidity,  in  cheese 296 

cream  of  tartar 343 

distilled  liquors 243 

prepared  mustard , 322 

total,  in  coffees 333 

fruits  and  fruit  products 178 

tanning  liquors 55 

volatile,  in  coffees 333 

water-soluble,  of  feeds 119 

Acids,  fixed,  in  tomato  products 324 

vinegars 256 

wines 240 

insoluble,  in  fats  and  oils  (Hehner  number) 307 

mineral,  free,  in  fruits  and  fruit  products 179 

vinegars 258 

soluble,  in  fats  and  oils 306 

total,  in  beers 250 

canned  vegetables 186 

tomato  products ; 324 

vinegars 256 

wines 238 

volatile,  in  beers 250 

canned  vegetables 186 

fruits  and  fruit  products 178 

tomato  products 324 

vinegars 256 

wines 239 

insoluble,  in  fats  and  oils  (Polenske  number) 308 

soluble,  in  fats  and  oils  (Reicherl-Meissl  number) 307 

Agar  agar 180 

Albrech  Method  for  lemon  and  orange  peel  color 264 

Albumin,  in  milk 288 

wheat  flour 188 

Alcohol,  in  beers 249 

confectionei^y 132 

distilled  liquors 243 

flavoring  extracts 259,  262,  266,  267,  268 

367 


368  INDEX 

Alcohol,  in  fruits  and  fruit  products 177 

vinegars 253 

wines 193 

extract,  in  spices 318 

precipitate,  in  fruits  and  fruit  products 179 

vinegars 257 

Aldehydes,  in  distilled  liquors 244 

total,  in  flavoring  extracts 262,  265 

Alkali,  black,  in  irrigating  water 51 

Alkalies,  total,  in  soils 27 

Alkalinity,  in  industrial  water 50 

Allihn's  Method  for  dextrose 106 

Almond  extract 266 

Alum,  in  baking  powders 345 

Aluminium,  in  soils 22 

waters 43 

oxid,  in  plants 30 

Amaranth 158 

Ammonia,  in  baking  powders 346 

meat  and  meat  products 274,  281 

free  and  albuminoid,  in  waters 36,  41 

Amthor  Test  Modified  by  Lasche  for  caramel 248 

Anise  extracts 269 

Annatto 168 

Antipyrin 354 

Arsenic,  in  baking  powders 350 

foods 171 

mineral  water 48 

oxid,  total,  in  insecticides  and  fungicides 66 

water-soluble,  in  insecticides  and  fungicides 67,  68,  72 

total,  in  insecticides  and  fungicides 63,  68,  69,  71,  72 

Arsenious  oxid,  sodium  acetate-soluble,  in  insecticides  and  fungicides 65 

total,  in  insecticides  and  fungicides 64,  66,  69,  71 

water-soluble,  in  insecticides  and  fungicides 65,  67,  72 

Ash,  in  baking  powders 345 

beers 250 

cacao  products 327 

canned  vegetables 185 

coffees 331 

dairy  products 287,  292,  293,  294,  296 

distilled  liquors 243 

flavoring  extracts 260,  264 

foods  and  feeding  stuffs 79 

fruits  and  fruit  products i 178 

leathers 59 

meat  and  meat  products 271,  280 

plants 29 

saccharine  products 128,  133,  137 

spices  and  other  condiments 317,  321,  323 

tea 335 

vinegars 


256 


INDEX  369 

.\sh,  in  wheat  flour 187 

wines 238 

Babcock  Method  for  fat  in  dairy  products 289,  292,  298 

Bacteria,  in  tomato  pulp,  etc 325 

Baking  powders 339-350 

Batnihl  Test  for  gluten  in  wheat  flour 189 

Baudoin  Test  for  sesame  oil 314 

Beef  fat,  in  lard 314 

Beers 249-251 

Benedikt-Lewkoivitsch  Method  for  acetyl  value  in  fats  and  oils 310 

Modified,  for  moisture  in  soap 73 

Benzaldehyde,  in  almond  extract 266 

Benzoic  acid 143-145 

Beta-Naphthol 151 

Blarez  Method,  Modified,  for  fluorids 149 

Borates 146 

Bordeaux  mixture 69 

with  lead  arsenate 72 

Paris  Green 71 

Boric  acid 146 

in  mineral  water 49 

Bromin,  in  mineral  water 47 

Butter 294 

renovated 295 

Butyric  acid,  in  tomato  products 324 

Cacao  products 327-330 

Caffein,  in  coffees - 332 

drugs 352,  353,  354,  359,.  360 

tea 336 

and  acetanilid,  in  mixtures 351 

acetphenetidin  (phenacetin),  in  mixtures 353 

antipyrin,  in  mixtures 353 

acetanilid  and  codein  sulphate,  in  mixtures 359 

quinin  sulphate,  in  mixtures 359 

and  morphin  sulphate,  in  mixtures.  .  .   360 

Calcium,  in  mineral  water 43,  50,  51 

plants 31 

soils 23 

arsenate 69 

carbonate  required,  in  soils 28 

Canned  vegetables 185-186 

Capsicum,  in  ginger  extract 268 

Caramel,  in  distilled  liquors 248 

Carbon,  inorganic,  in  soils 19 

in  plants 29 

organic,  in  soils 18 

dioxid,  in  insecticides  and  fungicides 70,  71,  72 

mineral  water 42 

plant  ash 29 

available,  in  baking  powders 343 


370  INDEX 

Carbon,  dioxid,  residual,  in  baking  powders 343 

total,  in  baking  powders 339 

Carbonic  and  bicarbonic  acids,  in  waters 42,  49 

Casein,  in  dairy  products 287,  294 

milk  chocolate 329 

Cassia  extract 267 

Cereal  foods 187-191 

Chace  Method  for  pinene 265 

total  aldehydes  in  flavoring  extracts 262,  265 

Cheese 296 

Chicory,  in  coffee 334 

Chlorin,  in  butter 294 

cyanids 73 

meat  extracts 280 

plants 32,  33 

waters 38,  41,  49,  51 

wheat  flour 189 

wines 238 

Chlorophyll 168 

Cholesterol  and  phytosterol,  in  mixtures  of  animal  and  vegetable   fats 311 

Cinnamon  extract 267 

Citral,  in  flavoring  extracts 263,  265 

Citric  acid,  in  fruits  and  fruit  products 182 

Clarifying  reagents  for  optical  methods 82 

Clove  extract 267 

Coating  and  glazing  substances,  in  coffees 333 

Cochineal 168 

Codein  sulphate 359 

Coffee,  green 331 

roasted 331 

Coffees 331-334 

Color,  in  beers 249 

potable  water 35 

vinegars 257 

residual,  in  vanilla  extract 261 

value,  in  vanilla  extract 261 

wheat  flour 191 

water-insoluble,  in  whiskies 248 

Coloring  matters 155-169 

in  dairy  products 292,  293,  295 

wines 240 

natural 163,  168 

separation  by  immiscible  solvents 157 

Colors,  insoluble  in  amyl  alcohol,  in  distilled  liquors 248 

vanilla  extract 261 

Condensed  milk  (sweetened) 293 

(unsweetened) 293 

Condiments 317-326 

Cook  Method  for  glycerol  in  meat  extracts 285 

Copper,  in  foods 175 


INDEX  371 

Copper;  in  insecticides  and  fungicides 70,71,72 

carbonate 69 

oxid,  total,  in  insecticides  and  fungicides 65 

reducing  substances  in  spices  and  other  condiments 318,  322 

Cottonseed  oil 313 

Coumarin,  in  vanilla  extract 259 

Cowles  Method  for  malic  acid  value 13S 

Cream 292 

of  tartar  in  wines 240 

Creatin,  in  meat  and  meat  products 275,  284 

Creatinin,  in  meat  extracts 285 

Crude  fiber,  in  cacao  products 327 

cofifees 333 

foods  and  feeding  stuffs 118 

spices  and  other  condiments 318,  322 

tea 336 

wheat  flour 187 

Cyanids,  sodium  and  potassium 72 

Dairy  products 287-298 

Dextrin,  in  beers 250 

fruits  and  fruit  products 179 

honey I34 

vinegars 258 

wines 241 

Dextrose,  in  foods  and  feeding  stuffs 106 

honey I34 

Diastase,  in  honey 136 

Distilled  liquors 243-248 

Drugs 351-366 

Dulcin 152 

Dyes,  acid I59 

basic 159 

coal  tar I55 

oil-soluble 156 

Emery  Method  for  beef  fat  in  lard 314 

Erythrosine 158 

Esters,  in  distilled  liquors 244 

Ether  extract,  in  butter 294 

confectionery 131 

foods  and  feeding  stuffs 80 

meat 271 

prepared  mustard 322 

wheat  flour 187 

volatile  and  non-volatile,  in  spices 318 

Extract,  in  beers 249 

distilled  liquors 243 

wines 236 

cold  water-soluble,  in  wheat  flour 188 


372  INDEX 

Facing,  in  tea 337 

Fat,  in  cacao  products 328 

coffees 334 

dairy  products 289,  292,  293,  295,  297 

leathers 59 

meat  extracts 280 

Fats  and  oils 299-315 

Fatty  acids,  free,  in  fats  and  oils 310 

liquid  and  solid,  in  fats  and  oils 309 

Feder  Anilin  Chlorid  Test  for  commercial  invert  sugar 136 

Ferric  oxid,  in  plants 30 

Fertilizers 1-15 

Fiehe  Test  (Bryan  Modification)  for  commercial  invert  sugar 135 

Fincke  Method  for  formic  acid  in  vinegars ^ 257 

Fish  oil,  in  the  presence  of  vegetable  oils 315 

Flavoring  extracts 259-269 

Flour,  wheat 187 

Fluoborates 149 

Fluorids 149 

Fluosilicates 149 

Folin  Aeration  Method  for  ammonia  in  meat 274 

Food  preservatives 141-154 

Foods  and  feeding  stuffs 79-119 

Formaldehyde 147-149 

solutions 75 

Formic  acid 152 

in  vinegars 257 

Fruit  products 177-184 

Fruits 177-184 

Fungicides 63-77 

Furfural,  in  distilled  liquors 244 

Fusel  oil,  in  distilled  liquors 245 

Galactan,  in  foods  and  feeding  stuffs 118 

Gelatin,  as  coating  substance,  in  coffees 334 

dairy  products 291,  293 

fruits  and  fruit  products 180 

meat  and  meat  products 274,  281 

Ginger,  in  ginger  extract 268 

cold-water  extract 318 

extract 267 

Glazing  substances,  in  coffees 333 

Globulin,  in  wheat  flour 188 

Glucose,  in  leathers 60 

commercial,  in  fruits  and  fruit  products 179 

saccharine  products 130,  135 

wines 237 

Gluten,  in  wheat  flour 189 

Glutenin,  in  wheat  flour 188 

Glycerol,  in  beers 250 

flavoring  extracts 259,  262 


INDEX  373 

Glycerol,  in  meat  extracts 285 

vinegars 253 

wines 236 

Glycogen,  in  meat 276 

Goldenberg-Geromonl-Heidenhain  Method  for  total  tartaric  acid  in  baking  powders  343 

Gorier  Method  for  caflfein  in  cofifee 332 

Gum,  in  wines 241 

Gunning  Method  for  organic  and  ammoniacal  nitrogen  in  fertilizers 7 

Modified,  for  total  nitrogen  in  fertilizers 8 

Halphen  Test  for  cottonseed  oil 313 

Hanus  Method  for  iodin  absorption  number  of  fats  and  oils 305 

Hardness,  permanent,  in  industrial  water 51 

temporary,  in  industrial  water 50 

total,  in  industrial  water 51 

Hay  Method,  Modified,  for  nitroglycerin  in  tablets 362 

Hedges  Method,  Modified,  for  total  arsenious  oxid  in  insecticides  and  fungicides    64 

Hehner  Method  for  formaldehyde 147 

free  mineral  acids  in  vinegars 258 

number,  of  fats  and  oils 307 

Herzfeld  Gravimetric  Method  for  invert  sugar 98 

Modification  of  the  alcohol  extraction  method  for  sucrose  in  beets.  . . .   138 

Sachs  le  Docte  Method  for  sucrose  in  beets 139 

Hess  and  Prescott  Method,  Modified,  for  vanillin  and  coumarin 259 

Hide  substance,  in  leathers 61 

Hiltner  Method  for  citral  in  flavoring  extracts 263,  265 

Honey 133-136 

Hortvet  Method  for  volatile  acids  in  wines 239 

and  West  Method  for  oil  in  anise  and  nutmeg  extracts 269 

cassia,  cinnamon  and  clove  extracts 267 

Modified,  for  methyl  salicylate  in  wintergreen  extract  269 
Howard  Method,  Modified,  for  oil  in  peppermint,  spearmint  and  wintergreen  ex- 
tracts   268 

HUbl  Method  for  iodin  absorption  number  of  fats  and  oils 304 

Hydrocyanic  acid,  in  almond  extract 266 

Hydrogen  sulphid,  in  mineral  water 41 

Indigo  carmine 158 

Insecticides 63-77 

Insoluble  residue,  in  soils 22 

Invert  sugar,  in  foods  and  feeding  stuffs 85 

commercial,  in  honey 135 

Iodin,  in  mineral  water 47 

absorption  number  of  fats  and  oils 304 

Iron,  in  mineral  water 43 

soils 22 

and  aluminium  in  mineral  water 42,  50 

Jorisscn  Method  for  sucrol  or  dulcin 152 

Test  for  salicylic  acid 142 


374  INDEX 

Kissling  Method  for  nicotin  in  tobacco  and  tobacco  extract 73 

Kjeldahl  Method  for  organic  and  ammoniacal  nitrogen  in  fertilizers 5 

Modified,  for  total  nitrogen  in  fertilizers 8 

-Gunning-Arnold  Method  for  organic  and  ammoniacal  nitrogen  in  ferti- 
lizers         7 

Kleber  Method  for  citral  in  lemon  and  orange  oils 265 

Koettstorfer  number  of  fats  and  oils 306 

Lactose,  in  cacao  products 329 

dairy  products 288,  292,  293 

foods  and  feeding  stuffs 104 

La  Wall  Method,  Modified  by  Doyle,  for  capsicum  in  ginger  extract 268 

Leach  and  Lythgoe  Method  for  methyl  alcohol  in  distilled  liquors 247 

Method  for  coloring  matters  in  milk 292 

formaldehyde 148 

Lead,  in  baking  powders 346 

arsenate 67-69 

number,  in  maple  products 137 

vanilla  extract 260 

oxid,  total,  in  insecticides  and  fungicides 67,  72 

precipitate,  in  vinegars 255 

Leathers 59-61 

Leffman  and  Beam  Method  for  soluble  volatile  acids  in  fats  and  oils 308 

Lemon  extracts 261 

oil 264 

in  lemon  extract 262 

and  orange  peel  color 264 

Levant  Wormseed 361 

Levulose,  in  honey 134 

Light  Green  S  F  yellowish 159 

Lime-sulphur  solutions 76-77 

Lindo-Gladding  Method  for  potash  in  fertilizers 12 

Lithium,  in  mineral  water 45 

London  purple 66-67 

Low,  A.  H.,  Volumetric  Method,  Modified,  for  determining  the  amount  of  reduced 

copper 96 

Lowenthal  Method,  Proctor  Modification,  for  tannin  in  tea 336 

Magnesium,  in  mineral  water 44,  50,  51 

plants 31 

soils 23 

Malic  acid,  in  fruits  and  fruit  products 181 

value,  in  maple  products 138 

Maltose,  in  foods  and  feeding  stuffs , 102 

Manganese,  in  mineral  water 47 

plants 31 

soils 23 

Maple  products 136- 138 

Marcusson  and  Schilling  Method  for  cholesterol  and  phytosterol 312 

Marr  Method,  Modified,  for  inorganic  carbon  in  soils 19 

Marsh  Method,  Modified,  for  color  insoluble  in  amyl  alcohol 248 


INDEX  375 

Mayrhofer  Method,  Price  Modification,  for  starch  in  meat 276 

McGill  Method,  Modified,  for  starch  in  baking  powders 345 

Meat 271 

bases  in  meat 274 

extracts 280 

and  meat  products 271-286 

Melting  point  determinations 301 

Metals,  in  foods 171-176 

Methyl  alcohol,  in  distilled  liquors 246 

flavoring  extracts 261,  264 

salicylate,  in  wintergreen  extract 269 

Micro-analysis  of  tomato  pulp,  ketchup,  puree  and  sauce  (paste) 324 

Milk 287-292 

fat,  in  milk  chocolate 328 

Mitchell  Method  for  lemon  and  orange  oils 262 

Mohler  test,  Modified,  for  benzoic  acid 144 

Moisture,  in  cacao  products 327 

canned  vegetables 185 

coffees 331 

dairy  products 294,  296 

fertilizers 1 

foods  and  feeding  stuffs 79 

insecticides  and  fungicides 63,  66,  67,  69,  71,  72 

leathers 59 

meat  and  meat  products 271 ,  280 

saccharine  products 121,  133,  136 

soils 17 

spices 317 

tea 335 

wheat  flour 187 

Molds,  in  tomato  pulp,  etc 324 

Morphin  sulphate 360 

Morpurgo  Method  for  sucrol  or  dulcin 152 

Munson  and  Walker  Method  for  reducing  sugars 86 

Mustard,  prepared 321 

Muter  Method,  Modified  by  Lane,  for  liquid  and  solid  fatty  acids 309 

Naphthol  Yellow  S 158 

Nitrates,  in  fertilizers 5 

meat  and  meat  products 278,  285 

wines 241 

Nitrobenzol,  in  almond  extract 267 

Nitrogen,  in  fertilizers 5-12 

leathers 61 

nitrate  salts,  in  fertilizers 11 

non-volatile  ether  extract,  in  spices 317 

saccharine  products 129 

albuminoid,  in  foods  and  feeding  stuffs 80 

alcohol-soluble,  in  meat  extracts 284 

amino,  in  foods  and  feeding  stuffs 80 

meat  extracts 282 


376  INDEX 

Nitrogen,  amino,  in  wheat  flour 188 

ammoniacal,  in  fertilizers 10 

connective  tissue,  in  meat 273 

nitrate,  in  waters 37,  41,  49 

nitric  and  ammoniacal,  in  fertilizers 10 

nitrite,  in  waters 37,  41 

wheat  flour 190 

organic  and  ammoniacal,  in  fertilizers 5 

in  fertilizers 11 

soluble  and  insoluble,  in  meat 273 

total,  in  cacao  products 327 

dairy  products 287,  292,  296 

fertilizers 8-10 

meat  and  meat  products 273,  280 

soils 21 

spices 317 

Nitroglycerin,  in  tablets 361 

Non tannins,  in  tanning  materials 54,  55 

Nutmeg  extracts 269 

Odor,  in  potable  water 35 

Oil,  in  anise  and  nutmeg  extracts 269 

cassia,  cinnamon  and  clove  extracts 267 

peppermint,  spearmint  and  wintergreen  extracts 268 

Oleomargarine 295 

Olive  oil,  in  paprika 319 

Orange  extract 261 

oil 264 

in  orange  extract 262 

1 158 

Oxygen,  dissolved,  in  potable  water 40 

required,  in  potable  water 39 

Parafiin,  in  confectionery 132 

tea 337 

Paris  Green 63-66 

Peanut  oil 313 

Pellet  Aqueous  Method  for  sucrose  in  beets 139 

Pentosans,  in  foods  and  feeding  stuffs 110 

vinegars 257 

wines 241 

Peppermint  extract 268 

Pepsin,  in  liquids 363 

Peptones,  in  meat  and  meat  products 274 

Petroleum  ether  extract,  in  coffees 333 

tea 335 

Phosphoric  acid,  in  baking  powders 346 

beers 250 

fertilizers 1-5,  14 

mineral  water 46 

plants 31 


INDEX  377 

Phosphoric  acid,  in  soils 22,  24 

wines 238 

soluble  and  insoluble,  in  vinegars 256 

Phosphorus,  soluble  in  N/5  nitric  acid,  in  soils 27 

total,  in  meat  and  meat  products 271,  280 

soils 25 

water-soluble,  in    meat 271 

Phytosterol,  in  mixtures  of  animal  and  vegetable  fats 311 

Pigments 155 

used  in  tea  for  coloring  or  facing 337 

Pinene,  in  lemon  and  orange  oils 265 

Plant  constituents 29-33 

Polarization,  in  foods  and  feeding  stuffs 83,  84 

fruits  and  fruit  products 179 

saccharine  products 129,  133,  136 

vinegars 255 

wines 237 

direct,  in  beers 250 

Polenske  Method  for  insoluble  volatile  acids  in  fats  and  oils 308 

number,  of  fats  and  oils 308 

Ponceau  3R 158 

Potash  in  fertilizers 12-14 

Potassium,  in  mineral  water 45 

plants 32 

soils 24 

total 26 

bitartrate  in  baking  powders 344 

Preservatives,  in  foods 141-154 

milk 291 

wines 242 

Protein,  in  beers 251 

condensed  milk 293 

fruits  and  fruit  products 179 

prepared  mustard 322 

tea 336 

wheat  flour 187 

alcohol-soluble,  in  wheat  flour 187 

coagulable,  in  meat  and  meat  products 274,  281 

crude,  in  foods  and  feeding  stuffs 80 

wines 241 

insoluble,  in  meat  extracts 281 

Proteoses,  in  meat  and  meat  products 274,  281 

Quinin  sulphate 359,  360 

Raffinose,  in  beet  products 84 

Raw  sugars,  general  directions  for  optical  methods 81 

Read  Method  for  pigments  used  in  tea  for  coloring  or  facing 337 

Reducing  substances,  total,  before  inversion,  in  vinegars 255 

sugars,  in  beers 250 

foods  and  feeding  stuffs 85,  109 


378  INDEX 

Reducing  sugars,  in  fruits  and  fruit  products 179 

saccharine  products 131,  134,  137 

wines 237 

after  inversion,  in  tomato  products » 324 

vinegars 255 

before  inversion,  in  tomato  products 323 

vinegars 255 

other  than  dextrose,  in  foods  and  feeding  stuffs 109 

Refractive  index,  of  fats  and  oils 300 

lemon  and  orange  oils 264 

Reichert-Meissl  Method  for  soluble  volatile  acids  in  fats  and  oils 307 

number,  of  fats  and  oils 307 

Renard  Test,  Modified,  for  peanut  oil 313 

Resin  oil 313 

Riche  and  Bardy  Method  for  methyl  alcohol  in  distilled  liquors 246 

Rimini  Method  for  formaldehyde 148 

Roese-Gottlieb  Method  for  ether  extract  in  confectionery 131 

fat  in  dairy  products 289,  293 

Saccharin 145 

Saccharine  products 121-139 

Sachsse  Method,  Modified,  for  starch 110 

Salicylic  acid 141-143 

Salol,  in  drugs 357 

Salt,  in  canned  vegetables 185 

dairy  products 294,  296 

prepared  mustard 321 

Sand,  in  plants 29 

tomato  products 323 

Sangle-Ferriere  Method  for  abrastol 152 

Saponification  number  of  fats  and  oils  {Koettstorfer  number) 306 

Schlosing-Wagner  Method  for  nitrates  in  meat 278 

Schmidt-Bondzynski  Method,  Modified,  for  fat  in  cheese 297 

Schuhe-Trommsdorf  Method  for  required  oxygen  in  water 39 

Seeker  Method  for  ginger  in  ginger  extract 268 

Serum,  acetic,  in  milk 291 

copper,  in  milk 291 

sour,  in  milk 291 

Sesame  oil 314 

Silica,  in  mineral  water 42,  49 

plants 29 

Sinibaldi  Method  for  abrastol 151 

Slag,  Thomas  or  basic 14-15 

Smith,  J.  Lawrence,  Method  for  total  alkalies  in  soils 27 

Method,  Modified,  for  total  arsenious  oxid  in  insecticides  and  fungicides.     65 

Soap 73 

Soda  lye 73 

Sodium,  in  mineral  water 45 

plants 32 

soils 24 

chlorid,  in  tomato  products 323 


INDEX  379 

Sodium  salicylate 368 

Soils 17-28 

Solids,  in  dairy  products 287,  292,  293 

flavoring  extracts 260,  264,  267 

fruits  and  fruit  products 177 

leathers 61 

saccharine  products 122 

spices  and  other  condiments 321,  323 

tanning  materials 53,  55 

vinegars 255 

waters 35,  41,  49,  51 

insoluble,  in  tomato  products 323 

non-sugar,  in  wines 237 

soluble,  in  coffees 331 

Soxhlet  Method  for  dextrose 106 

invert  sugar  in  foods  and  feeding  stuffs 86 

Wein  Method  for  lactose 104 

Spdth  Method  for  fats  and  waxes  in  coffee 334 

Spearmint  extract 268 

Special  tests  for  coal  tar  dyes  permitted  under  the  Federal  Food  and  Drugs  Act.  162 

Specific  gravity,  in  beers 249 

distilled  liquors 243 

fats  and  oils 299 

flavoring  extracts 259,  261,  264 

saccharine  products 122 

vinegars 253 

wines 193 

Spices 317 

microscopic  examination  of 319 

and  added  pungent  materials  in  vinegars 258 

other  condiments 317-326 

Spores,  in  tomato  pulp,  etc 325 

Stahlschmidt  Method,  Modified,  for  caffein  in  coffee 332 

Starch,  in  baking  powders 344 

cacao  products 328 

coffees 333 

foods  and  feeding  stuffs 110 

fruits  and  fruit  products 180 

meat 276 

saccharine  products 131 

spices 318 

Strontium,  in  mineral  water 44 

Sucrol 152 

Sucrose,  in  cacao  products 329 

condensed  milk 293 

flavoring  extracts 260,  264 

foods  and  feeding  stuffs 81-85 

fruits  and  fruit  products 179 

saccharine  products 129,  134,  137,  138 

tomato  products. .' 324 

wines 237 


380  INDEX 

Sugar,  as  a  coating  and  glazing  substance,  in  coffees 333 

house  products 138 

Sugars,  in  canned  vegetables 186 

cattle  foods 109 

distilled  liquors 246 

meat  and  meat  products 278,  285 

wheat  flour 187 

Sulphite-cellulose,  in  tanning  materials 54 

Sulphuric  acid,  in  baking  powders 346 

mineral  water 44,  50,  51 

plants 32 

soils 24 

wines 238 

Sulphur,  in  mustard 319 

plants 32 

Sulphurous  acid 150 

Sweetening  substitutes,  in  fruits  and  fruit  products 184 

Tannin,  in  cloves  and  allspice 319 

leathers 61 

tanning  materials 54 

tea 336 

wines 240 

Tanning  extracts 53 

liquors 55 

materials 53-57 

raw  and  spent 56 

Tartaric  acid,  free,  in  baking  powders 344 

wines 240 

or  combined  in  baking  powders 343 

total,  in  baking  powders 343 

fruits  and  fruit  products 180 

vinegars 257 

wines 240 

and  tartrates  in  vinegars 257 

Tartrazine 158 

Tea 335-337 

Thomas  or  basic  slag 14-15 

Tin,  in  foods 173 

Titer  test  for  fats  and  oils 302 

Tobacco  and  tobacco  extract 73-75 

Tomato  products 322 

Tragacanth 360 

Trillat  Method  for  methyl  alcohol  in  distilled  liquors 246 

Trowbridge  and  Francis  Method  for  glycogen  in  meat 277 

Turbidity,  in  potable  water 35 

Turmeric 168 

Turpentine 365 

Ulsch-Street  Method  for  nitric  and  ammoniacal  nitrogen  in  fertilizers 10 


INDEX  381 

Unsaponifiable  residue,  in  fats  and  oils 312 

Vanilla  extract  and  its  substitutes 259 

resins 260 

Vanillin,  in  vanilla  extract 259 

Van  Shjke  Method  for  amino  nitrogen  in  meat  extracts 282 

Villavecchia  Test  for  sesame  oil 314 

Vinegars 253-258 

Volatile  matter,  in  soils 17 

oil,  in  tea 336 

Volhard  Method  for  chlorin  in  plant  ash 32 

Water  extract,  acidity  of,  in  wheat  flour 187 

in  tea 335 

industrial 49-51 

irrigating , 51-52 

mineral 41-49 

potable 35-41 

Waters 35-52 

Water-soluble  material,  in  leathers 59 

Waxes,  in  coffees 334 

Wein  Method  for  maltose 103 

Wiley  Method  for  melting  point  of  fats  and  fatty  acids 301 

Wines 193-242 

Winkler  Method,  as  Modified  by  Drown  and  Hazen,  for  dissolved  oxygen  in  water    40 
Rideal  and  Stewart,  for  dissolved  oxygen  in  water    40 

Wintergreen  extract 26S 

Winlon  Method  for  soluble  solids  in  coffees 331 

Ogden  and  Mitchell  Method  for  nitrogen  in  non-volatile  ether  extract. .  317 
Wolff  Method  for  free  or  combined  tartaric  acid  in  baking  powders 343 

Yeasts  and  spores,  in  tomato  pulp,  etc 325 

Zinc,  in  foods 175 

arsenite 69 


THE  END 


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